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Year levels.

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Expected level of development

Australian Curriculum Mathematics V9 : AC9M7M04 and AC9M7M05

Numeracy Progression : Understanding geometric properties: P6

At this level, students identify corresponding, alternate and co-interior angles on parallel lines crossed by a transversal (a line that intersects two or more parallel lines). They apply this learning to geometrically prove that interior angles of a triangle sum to 180, and then extrapolate to all convex polygons.

It is important for students to construct parallel lines using a protractor and ruler, providing an opportunity for them to understand what it means for lines to ‘point in the same direction’. Students should know that parallel lines never intersect. This is where the concept of a transversal can be introduced, with students discovering that the angles formed at each line will always be identical. It is crucial students see that this concept is the nature of parallel lines. Ask questions so that they can explain ‘why’, using their new knowledge.

Constructing perpendicular lines with compasses is an excellent independent activity for students. ‘Who can figure out a method to construct two perfectly perpendicular lines without a protractor?’ For context and engagement, students could first learn how Ancient Greeks made mathematical discoveries using only a compass and straight-edge, without the measuring tools we have today. The activity can conclude by cementing the fact that perpendicular angles always intersect at a right angle.

Introduce students to formal geometric proof, investigating the interior angle sum of a triangle, with a focus on the reasons why it is true. Discuss what is important as justification. Connect the interior angle proof for triangles to other polygons. With concrete materials students can construct a range of polygons using only triangles and record the number of triangles it takes to construct polygons with varying numbers of sides. Conclude the reasoning by stating the angle sum formula for all convex polygons.

Diagrams are vital to help students recognise corresponding, alternate, and co-interior angles. Presenting examples of parallel lines drawn at different orientations ensures students can recognise these angles in a range of contexts. To support understanding, it is recommended that students learn via hands-on activities such as measuring angles or using dynamic geometry software.

Highlight the value of logical and consistent labelling when constructing or working with diagrams involving angles and lines to help solve or model problems. Practise naming angles and segments from labelled diagrams as well as labelling diagrams themselves. Using the correct symbols and notation should be regarded as essential to correctly solving problems.

Teaching and learning summary:

  • Identify and classify angles as corresponding, alternate or co-interior on parallel lines crossed by a transversal.
  • Construct parallel and perpendicular lines using their properties, compasses, protractors, and a ruler, or geometry software.
  • Connect and build on students’ prior knowledge of angles and related areas.
  • Develop students’ vocabulary of terms relating to angles and geometry.
  • Label and interpret diagrams involving lines and angles and use mathematical notation to name different elements.
  • Challenge students to use their vocabulary and notation when solving problems or providing justification for a solution.
  • Recognise the conditions for lines to be parallel and perpendicular.
  • Demonstrate how to construct angles, parallel lines and perpendicular lines.
  • Prove the interior angle sum for triangles using parallel lines and alternate angles. Expand this theorem to polygons in general.

angles problem solving year 7

  • recognise and classify angles according to their properties
  • understand and use the correct vocabulary and notation associated with geometry
  • solve problems using the properties of angles, parallel lines and the interior angle sum
  • explain and justify their solutions with correct notation and vocabulary
  • recognise lines as parallel and perpendicular
  • construct angles and parallel lines using compasses and a ruler
  • use dynamic geometry software to construct angles and shapes.

Some students may:

  • have difficulty distinguishing between corresponding and co-interior angles as they are both on the same side of the transversal. Memory tricks and plenty of practice are vital
  • have difficulty identifying parallel lines when they are drawn at orientations other than vertical or horizontal or accepting that lines are parallel if they are labelled with arrows but don’t look perfectly aligned
  • be overwhelmed with the new notation, vocabulary, and naming conventions
  • experience difficulties determining what constitutes adequate reasoning when writing a proof
  • confuse the upper and lower scales when measuring angles using a 180°-degree protractor
  • associate 360 as being ‘full’ or ‘complete’ and think that the angle sum is always 360.

To help with these challenges, create interesting rules like 'corresponding angles make an F shape' or 'co-interior angles make a C shape'. Ensure students confirm that the lines are parallel before identifying angles as corresponding, co-interior or alternate and reinforce that the relationships only apply in this case.

The Learning from home activities are designed to be used flexibly by teachers, parents and carers, as well as the students themselves. They can be used in a number of ways including to consolidate and extend learning done at school or for home schooling.

Learning intention

  • I can identify and determine the purpose of parallel and perpendicular lines in our physical world.
  • I can prove the interior angle sum for a triangle.
  • I will understand and use the correct vocabulary and notation associated with geometry.

Why are we learning about this?

No matter where you look you are bound to find parallel and perpendicular lines. We use their properties to make our buildings strong and sport fields fair. Understanding these properties, and the angles they form, means we can harness their power too.

Grab your camera and free up some storage, we’ve got lots of photos to take!

  • Find as many examples of parallel and perpendicular lines as you can around your home, garden, or neighbourhood.
  • Snap a photo of each.
  • Once you’re happy with the album you’ve put together, find a pen and paper, or your laptop.
  • For each photo try and explain why the parallel or perpendicular lines are present there, and what value they provide. For example, why is your phone screen framed by two sets of parallel lines, one set perpendicular to the other? Yes, you’re right, they make a rectangle. But why is that a good choice for a phone screen? Why not have slanted sides?

angles problem solving year 7

  • By adding only a single line to this diagram that creates a pair of parallel lines, can you prove that all angles in a triangle must add up to 180°.
  • To achieve this, you will need to carefully label the angles so you can refer to them in your reasoning.
  • Ask yourself, does the proof I’ve provided have adequate reasons to justify it? Hint: can you connect a set of angles that form a straight angle with the angles inside the triangle?

Success criteria

  • I can identify parallel and perpendicular.
  • I recognise the conditions for lines to be parallel and perpendicular and describe why they are valuable in our world.
  • I understand and use the correct vocabulary and notation associated with geometry.

Please note:  This site contains links to websites not controlled by the Australian Government or ESA. More information  here .

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Teaching strategies.

A collection of evidence-based teaching strategies applicable to this topic. Note we have not included an exhaustive list and acknowledge that some strategies such as differentiation apply to all topics. The selected teaching strategies are suggested as particularly relevant, however you may decide to include other strategies as well. 

Worked examples Image

Worked examples

A worked example is not just a pre-worked question that is given to the students. There are several types of worked examples and ways of using them.

Concrete, Representational, Abstract (CRA) Image

Concrete, Representational, Abstract (CRA)

The CRA model is a three-phased approach where students move from concrete or virtual manipulatives, to making visual representations and on to using symbolic notation.

Explicit teaching Image

Explicit teaching

Explicit teaching is about making the learning intentions and success criteria clear, with the teacher using examples and working though problems, setting relevant learning tasks and checking student understanding and providing feedback.

Mathematics investigation Image

Mathematics investigation

By giving students meaningful problems to solve they are engaged and can apply their learning, thereby deepening their understanding.

Teaching resources

A range of resources to support you to build your student's understanding of these concepts, their skills and procedures. The resources incorporate a variety of teaching strategies.

Angles and parallel lines Image

Angles and parallel lines

In this lesson, students will engage in various activities to explore angles between parallel lines in a navigational context.

Parallel lines and angle sum of a triangle Image

Parallel lines and angle sum of a triangle

This resource focuses on drawing representations of solid objects and gives detailed explanations of the curriculum content, with worked examples and assessment questions.

Introduction to plane geometry  Image

Introduction to plane geometry

This module is for teachers who wish to consolidate their content knowledge on the topic of two-dimensional geometry.

Alternate interior angles  Image

Alternate interior angles

First of a series of lessons that explore angles and parallel lines using dynamic geometry.

Parallel lines & related angles Image

Parallel lines & related angles

This resource contains multiple activities that demonstrate the properties of angles and parallel lines together with assessment.

Relevant assessment tasks and advice related to this topic.

By the end of Year 7, students can apply knowledge of angle relationships and the sum of angles in a triangle to solve problems and apply this to other shapes and the size of unknown angles. Students can explain their thinking and reasons.

Parallel lines and the angles in a triangle Image

Parallel lines and the angles in a triangle

In this activity students find the missing angle in a triangle and identify angles on parallel lines.

Alternate interior angles assessment activity Image

Alternate interior angles assessment activity

In this activity students identify and find the size of alternate angles.

Supplementary angles  Image

Supplementary angles

In this activity students are shown what constitutes a supplementary angle and answer a series of questions to demonstrate their understanding.

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Part 4: Angle Relationships

maths-guide-year-7-angle-relationships-header-banner

Guide Chapters

  • 1. Fractions
  • 2. Decimals and Percentages
  • 3. Algebraic techniques
  • 4. Angle Relationships
  • 7. Data collection & representation
  • 8. Pythagoras' theorem

Angle relationships is an essential topic because it forms the foundation of many different Maths topics that you will come across in the future. In this guide, we will give you the best tips to work with angle relationships.

Syllabus Outcomes

We will be looking at NSW Syllabus Outcomes:

 NSW Stage 4 Syllabus Outline
SyllabusExplanation
Demonstrate that the angle sum of a triangle is 180 and use this to find the angle sum of a quadrilateral (ACMMG166)This means that you will know how to identify and figure out angle sizes in supplementary angles.
Establish properties of quadrilaterals using congruent triangles and angle properties, and solve related numerical problems using reasoning (ACMMG202)This means that you know how to use different angles on a point and angles associated with parallel lines.
Identify, name and measure alternate angle pairs, corresponding angle pairs and co-interior angle pairs for two lines cut by a transversal (ACMMG163)This means that you can work out sizes on different angles by looking at alternate, corresponding and co-interior angle pairs.
Solve simple numerical problems using reasoning (ACMMG164) This means that you are able to questions like: “Find the value of \(  \alpha° \) in the diagram”

Why do students struggle with Angle Relationships?

Understanding and learning angle relationships may be easy… But the majority of students face difficulty when applying angle relationships.

They also struggle with presenting answers in a coherent way that’s not obtuse. This means that markers will struggle to follow the reasoning provided.

These are the main difficulties faced by students in this topic:

  • Providing a coherent set of reasons that a marker would understand
  • Writing out the complete reason for a certain angle relationship.

What’s in this article?

This guide will help you overcome these difficulties, as well as covering the following content:

  • Naming lines and angles
  • Complementary angles, supplementary angles and angles about a point
  • Vertically opposite angles
  • Angle relationships on parallel lines

Assumed Knowledge

To do well in Angle Relationships, you need to know about:

Naming Lines and Angles

Students should be familiar with how to name lines as well as angles.

Lines should be named as a group pair of letters.

For example, the diagram below shows the lines \( AB \).

maths-guide-year-7-assumed-knowledge-line-AB

To name angles, identify the vertex and the two letters at the end of each ray.

In the case below,

  • \( B \) is the vertex
  • \( A \) and \( B \) are the ends of each ray

maths-guide-year-7-assumed-knowledge-angle-ABC

To name the angle above, the middle letter should represent its vertex.

Thus the angle can be named as such:

\begin{align*} \angle ABC \ or \ \angle CBA \ or \ \angle B \end{align*}

Angles from a point

Complementary angles.

Two angles that add up to \( 90º\) are called complementary angles.

  • The angles, \( \alpha \) and \( \beta \) are complementary angles, where \( \alpha + \beta = 90º \)

maths-guide-year-7-angle-relationships-complementary-angles

Supplementary Angles

Similarly, two angles that add up to \( 180º\) are called supplementary angles.

  • The angles \( \alpha \) and \( \beta \) are supplementary angles, where \( \alpha + \beta = 180º \)

maths-guide-year-7-angle-relationships-supplementary-angles

Angles at a Point (Angles in a revolution)

Angles at a point form a revolution add up to \( 360° \).

In the diagram below:

  • \( \alpha + \beta + \gamma + \delta = 360º \)

maths-guide-year-7-angle-relationships-angle-relationships-angles-at-a-point

1. Find the size of \( x \).

maths-guide-year-7-angle-relationships-angles-at-a-point-example

To determine the size of \( x \), we need to utilise the fact that angles at a point add to   \( 360°\).

As a result,

\begin{align*} x°+ 2x° + (x-30)° + 90° &= 360° \ (\text{Angles of a revolution add to} \ 360°) \\ 4x° – 30° + 90° &= 360° \\ 4x° &= 300° \\ ∴ x° &= 75º \end{align*}

Vertically Opposite Angles

When two straight lines intersect, the two pairs of opposite angles formed are equal.

These are known as vertically opposite angles.

  • \( AD \) and \( BC \) intersect at the point \( X \)

maths-guide-year-7-angle-relationships-vertically-opposite-angles

  • \(\angle CXA = \ \angle DXB \ (\text{Vertically opposite angles are equal}) \)
  • \(\angle CXD = \ \angle AXB \ (\text{Vertically opposite angles are equal}) \)

Angles Associated with Parallel Lines

Parallel lines.

Parallel lines are lines in a plane that do not intersect or touch each other at any point.

Notation : Parallel lines are marked with arrowheads pointing in the same direction.

In the diagram:

  • \( AB \) and \( CD \) and parallel

maths-guide-year-7-angle-relationships-transversal

To represent that \( AB \) and \( CD \) are parallel, we use the parallel symbol and notate as \( AB \parallel CD \)

A transversal is a line that crosses two or more lines.

In the diagram, the transversal \( EF \) cuts the lines \( AB \) and \( CD \).

maths-guide-year-7-angle-relationships-transversal-cuts-parallel-lines

Transversals which cross parallel lines, give rise to three fundamental parallel angle relationships ( Alternate, Corresponding and Co-interior angles ).

Alternate Angles

Alternate angles are angles on opposite sides of the transversal and between the parallel lines.

Alternate angles on parallel lines are equal.

In the diagram below,

  • \( \alpha \) and \( \beta \) are equal in size.

An example of written reasoning could be,

maths-guide-year-7-angle-relationships-alternate-angles

  • Alternate angles can be identified by a \( “Z” \) orientation as shown in the bold lines in the diagram below.

maths-guide-year-7-angle-relationships-alternate-angles-z-formation

Corresponding Angles

Corresponding angles are angles on same sides of the transversal. One angle is between the parallel lines while the other is outside. Corresponding angles on parallel lines are equal.

  • \( \alpha \) and \( \beta \) are equal in size.

maths-guide-year-7-angle-relationships-corresponding-angles

  • Corresponding angles can be identified by a \(“F”\) orientation as shown in the bold lines in the diagram below.

maths-guide-year-7-angle-relationships-corresponding-angles-f-formation

Co-Interior Angles

Co-interior angles are angles on same sides of the transversal between the parallel lines.

Co-interior angles are supplementary ( add up to \(180°\) )

  • \( \alpha \) and \( \beta\) are supplementary angles

maths-guide-year-7-angle-relationships-cointerior

An example of written reasoning could be:

  • \( \angle AXY + \angle CYX = 180º \ (\text{Co-interior angles on parallel lines} \ AB \ \text{and} \ CD \ \text{are supplementary}) \)

Co-interior angles can be identified by a “C” orientation as shown in the bold lines in the diagram below.

maths-guide-year-7-angle-relationships-cointerior-c-formation

1. Find the value of \( \beta \)

maths-guide-year-7-angle-relationships-corresponding-angles-example

\begin{align*} \angle EXB &= \angle AXY = 30° \ (\text{Vertically opposite angles are equal}) \\ \beta° &= 180° – \angle AXY \ (\text{Co-interior angles on parallel lines are supplementary})\\ \beta° &= 180° – 30° \\ \beta° &= 150° \end{align*}

Proving Lines are Parallel

Conversely, we can use these angle relationships to prove that two lines are parallel.

This occurs when one or more of the following relationships hold:

  • Alternate angles are equal
  • Corresponding angles are equal
  • Co-interior angles are supplementary

1. Prove that \( AF \) and \( CE \) are parallel

maths-guide-Year-7-angle-relationships-prove-lines-are-parallel-question-1

\begin{align*} <AXB &= \angle GXF = 79° \ \ (\text{Vertically opposite angles are equal}) \\ <YXF &= 180° – <HXG \ – \angle GXF \ \ (\text{Angle sum of straight lines}) \\ <YXF &= 180° – 70° – 79° \\ <YXF &= 31° \\ <YXF &= \angle DYE = 31°\\ ∴ AF \ &and \ CE \ are \ parallel \ \ (\text{Corresponding angles} \ \angle YXF \ \text{and} \ \angle DYE \ \text{are equal}) \end{align*}

  • To determine an angle given a diagram, first roughly work out the angle you’re trying to figure out.
  • Then, using the sample reasoning mentioned in the above content section, provide coherent reasoning to clearly list out steps required to reach the answer.

The following is a summary of the angle relationships covered in the post:

Angle relationshipDescriptionDiagramExplanation
Angles add to \( 90° \) \( \alpha + \beta = 90° \)
Angles add to \( 180° \) \( \alpha + \beta = 180° \)
Angles add to \( 360° \) \( \alpha + \beta + \gamma + \delta = 360° \)
Angles are equal \( \alpha =  \beta\)
Angles are equal \( \alpha =  \beta\)
Angles are equal \( \alpha =  \beta\)
Angles are supplementary  \( \alpha + \beta = 180° \)

Checkpoint questions

1. Given that \( \alpha° \) and \( \beta° \) are complementary, what is value of \( \beta° \) if  \( \alpha° = 54° \)

2. Find the value of \( \alpha° \) and \( \beta° \) in the following diagram 

maths-guide-year-7-angle-relationships-question-2

3. Prove that \( BC \) and \( DE \) are parallel.

4. Find the size of \( \alpha° \)

maths-guide-year-7-angle-relationships-question-3

5. Find the size of \( \alpha° \)

maths-guide-year-7-angle-relationships-question-5

\begin{align*} \beta° = 36° \end{align*}

\begin{align*} \beta° &= 180° – \angle AXB \ (\text{Angle sum of straight line}) \\ \beta° &= 94° \\ \angle EXC &= \angle AXB = 86° \ (\text{Vertically opposite angles are equal}) \\ \alpha° + 26° &= 86° \\ \alpha° &= 60° \end{align*}

\begin{align*} \angle{CBD} &= \angle{BAC} + \angle{ACB} \ (\text{Exterior angle sum of triangle}) \\ \angle{CBD} &= 126° \\ \angle{CBD} &+ \angle{BDE} \\ &= 126° + 54° \\ &= 180° \\ \end{align*}

\begin{align*} ∴ BC \ \text{and} \ DE \ \text{are parallel Co-interior angles , angles} \angle{CBD} \ \text{and} \ \angle{BDE} \text{are supplementary on parallel lines}) \end{align*}

\begin{align*} \angle CDA &= \angle DEB = 125° \ (\text{Corresponding angles on parallel lines} \ AK \ \text{and} \ BL \ \text{are equal}) \\ \angle DEB &= \angle HIE = 125° \ (\text{Corresponding angles on parallel lines} \ CF \ \text{and} \ GJ \ \text{are equal}) \\ \alpha° & = \angle HIE = 125° \ (\text{Vertically opposite angles are equal}) \end{align*}

5. Construct \( EF \) so that it is parallel to \( AB \) and \( CD \)

maths-guide-year-7-angle-relationships-solution-5

\begin{align*} \angle BEF &= 180° – 35° \ (\text{Co-interior angles on parallel lines} \ AB \ \text{and} \ EF \ \text{are supplementary}) \\ \angle BEF &= 145° \\ \angle CEF&= 180° – 46° \ (\text{Co-interior angles on parallel lines} \ CD \ \text{and} \ EF  \ \text{are supplementary}) \\ \angle CEF &= 134° \\ ∴\alpha° &= \angle BEF + \angle CEF \\ \alpha°  &= 279° \end{align*}

Part 5: Length

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7th Grade Angles Worksheets

7th grade angles worksheets are perfect for students to learn and practice various problems about different angle topics. These worksheets are a great resource for students who wish to expand and improve their skills in angles. These 7th grade math worksheets consist of concepts like naming angles, classifying angles, measuring angles using a protractor, identifying the parts of an angle, and many more interesting topics.

Benefits of 7th Grade Math Angles Worksheets

These worksheets help the students to gain a deep understanding of angles and their classifications. Students can review and time themselves too while solving these grade 7 angles worksheets.

With the help of 7th grade angles worksheets, students can enhance and strengthen their knowledge thus making the concepts of angles easier and exciting. 7th grade worksheets teach the students tips and tricks related to the concept of angles.

Printable PDFs for Grade 7 Angles Worksheets

Students can download the pdf format of angles worksheets for grade 7 to practice some questions for free.

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KS3 Angles (MEP – Year 7 – Unit 5)

KS3 Angles (MEP – Year 7 – Unit 5)

Subject: Mathematics

Age range: 11-14

Resource type: Lesson (complete)

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Last updated

25 June 2014

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Angles Test

Select your answers to the following 10 questions from the pop-up menus in the right hand column. Clicking the "Begin Test Again" button will clear all the answers.

 

 

 

is equal to:

A. 225

B. 65

C. 45

D. 135

Answer 1:

 

 

 and the angle marked y are:

A. corresponding angles

B. vertically opposite angles.

C. adjacent angles

D. alternate angles

Answer 2:

 

 

Two angles which add up to 90  are called: A. congruent angles
B. supplementary angles
C. complementary angles
D. acute angles
Answer 3:

 

 

The value of  is:

A. 145

B. 135

C. 90

D. 80

Answer 4:

 

 

For Angle ABC, the vertex is:

A. A B. B C. C D. D Answer 5:

 

 

angle?

A. 45 B. 90
C. 167
D. 225
Answer 6:

 

 

Another meaning for the word  is: A. vertically opposite 
B. supplementary
C. adjacent
D. equal
Answer 7:

 

 

and  are best described as:

A. supplementary angles B. vertically opposite angles C. complementary angles D. alternate angles Answer 8:

 

 

angles are: A. equal
B. supplementary
C. obtuse
D. adjacent
Answer 9:

 

 

A. 43
B. 45 C. 47
D. 137
Answer 10:

 

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Distinguish between lines, line segments, rays, perpendicular lines, and parallel lines.

Find the missing angle using complimentary and supplimentary angles.

Find the missing angle using complimentary and supplimentary angles. worksheet #1.

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Find the missing angle in the triangles and the covex quadrilaterals, worksheet #3.

  • Maths Questions

Angles Questions

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Angles questions and answers are available here to help students understand how to solve basic angles problems. These questions cover the different types of angles and their measures, and finding the missing angles when a pair or more than two angles are given in a specific relation. You will also get some extra practice questions at the end of the page. These will help you to improve your geometry skills and get a clear understanding of angles.

What are angles?

In geometry, angles are the figures formed by two rays that are connected by a common point called the vertex. We can measure the angles between two lines, rays or line segments using one of the geometric tools called a protractor. Based on the measure of these angles, we can classify them.

The different types of angles are listed below:

  • Acute angle (< 90°)
  • Obtuse angle (> 90° and < 180°)
  • Right angle (= 90°)
  • Straight angle (= 180°)
  • Reflex angle (> 180° and < 360°)
  • Full rotation angle (= 360°)

angles questions

Also, check: Angles

Angles Questions and Answers

1. Classify the following angles:

55° < 90°

Thus, 55° is an acute angle.

90° < 146° < 180°

So, 146° is an obtuse angle.

90° is a right angle.

180° < 250° < 360°

Thus, 250° is a reflex angle.

2. Write two examples of obtuse angles and reflex angles.

As we know, obtuse angles are the angles that measure less than 180° and greater than 90°.

Examples: 112°, 177°

Reflex angles measure less than 360° and greater than 180°.

Examples: 210°, 300°

Complementary angles: Sum of two angles = 90°

Supplementary angles: Sum of two angles = 180°

Linear pair of angles: Sum of angles = 180°

Sum of angles at a point = 360°

3. Find the measure of an angle which is complementary to 33°.

If the sum of two angles is 90°, they are called complementary angles.

Let x be the angle which is complementary to 33°.

So, x + 33° = 90°

x = 90° – 33° = 57°

Therefore, the required angle is 57°.

4. What is the measure of an angle that is supplementary to 137°?

If the sum of two angles is 180°, they are called supplementary angles.

Let x be the angle which is supplementary to 137°.

So, x + 137° = 180°

x = 180° – 137° = 43°

Hence, the required angle is 43°.

5. If three angles 2x, 3x, and x together form a straight angle, find the angles. Solution:

We know that straight angle = 180°

Given that the angles 2x, 3x, and x form a straight angle.

That means 2x + 3x + x = 180°

2x = 2 × 30° = 60°

3x = 3 × 30° = 90°

Therefore, the angles are 60°, 90° and 30°.

6. Are 125° and 65° supplementary angles?

As we know, the condition for supplementary angles is that they add up to 180°.

Given angles: 125°, 65°

Sum = 125° + 65° = 190°

Thus, 125° and 65° are not supplementary angles.

7. What is the measure of a complete angle?

The measure of a complete angle is 360°.

Two straight angles form a complete angle, i.e., 180° + 180° = 360°.

Four right angles form a complete angle, i.e., 90° + 90° + 90° + 90° = 360°.

8. Find the value of y if (4y + 22)° and (8y – 10)° form a linear pair.

According to the given,

(4y + 22)° + (8y – 10)° = 180°

4y + 22° + 8y – 10° = 180°

12y + 12° = 180°

12y = 180° – 12°

y = 168°/12

9. Three angles at a point are 135°, 75° and x. Find the value of x.

Given angles at a point are: 135°, 75°, x

As we know, the sum of angles at a point = 360°

So, 135° + 75° + x = 360°

210° + x = 360°

x = 360° – 210° = 150°

Therefore, the value of x is 150°.

10. If 3x + 24° and 5x – 16° are congruent, then find the value of x.

Congruent angles mean equal angles.

So, 3x + 24° = 5x – 16°

⇒ 5x – 3x = 24° + 16°

⇒ x = 40°/2

Thus, the value of x is 20°.

Practice Problems on Angles

  • Are 42° and 58° complementary angles?
  • How do you find the measure of an angle which is supplementary to 92°?
  • What is the condition for a reflex angle?
  • If 38° and 2x + 26° form a right angle, find the value of x.
  • Classify the following angles: (i) 72°
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Maths with David

Year 7. angles in parallel lines.

Corresponding Angles

Parallel lines occur a lot in life. Can you see any around you?

A transversal is the name we give to a line that cuts across a pair of parallel lines, like a road crossing a railway track.

When a transversal crosses a pair of parallel lines, it forms pairs of corresponding angles. These are always equal. Let’s see them on a diagram.

Worked Example

angles problem solving year 7

Alternate angles

As well as creating corresponding angles, a transversal crossing parallel lines also forms alternate angles. Let’s draw some diagrams to identify these.

In general the most important thing is that we know when two angles are equal, but we should also know why (i.e. if it is because they are corresponding, alternate, or vertically opposite) and we can also be tested to check that we know these classifications.

angles problem solving year 7

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9.02 Measuring angles

Angle types, measure angles, angle relationships.

An angle is formed between two lines, rays, or segments whenever they intersect. We can think of an angle as a turn from one object to the other.

The most important angle in geometry is called a right angle , and represents a quarter of a turn around a circle. When two objects form a right angle, we say they are perpendicular . We draw a right angle using a small square rather than a circular arc:

Two perpendicular segments.

We draw all other angles with a circular arc.

An angle that is smaller than a right angle is called an acute angle .

Two right angles together form a straight angle .

Four right angles is the same as two straight angles, making a full revolution .

An angle that is larger than a right angle but smaller than a straight angle is called an obtuse angle .

We met this kind of angle in the previous lesson - a reflex angle which is larger than a straight angle, but smaller than a full revolution.

Angles are a measure of turning. All angles can be compared to a right angle , representing a quarter turn.

Select the obtuse angle:

Use this image to help you:

Rotate each angle so that one arm lies over the start.

The answer is Option C.

Angles are a measure of turning. All angles can be compared to a right angle, representing a quarter turn.

We divide a full revolution up into 360 small turns called degrees , and write the unit using a small circle, like this: 360\degree .

Since 90 is one quarter of 360 , we know that a right angle is exactly 90\degree .

This circle has markings every 45\degree .

Exploration

We can measure angles more precisely using a protractor, or an applet like this one:

The applet shows the sizes of the different kind of angles: acute, right, obtuse, straight, reflex and full revolution.

This lets us associate numbers with the angle types we learned about above.

A full revolution is made up of 360 degrees, a single degree is written as 1\degree .

Angle typeAngle size
\text{Acute angle}\text{Larger than } 0 \degree, \text{ smaller than } 90\degree.
\text{Right angle}90\degree
\text{Obtuse angle}\text{Larger than } 90\degree, \text{ smaller than } 180\degree.
\text{Straight angle}180\degree
\text{Reflex angle}\text{Larger than } 180\degree, \text{ smaller than } 360\degree.
\text{Full revolution}360\degree

Select the angle that is closest to 120\degree :

A 120\degree angle would be an obtuse angle between 90\degree and 135\degree.

A full revolution is made up of 360 degrees, a single degree is written 1\degree .

Angle typeAngle size
\text{Acute angle}\text{Larger than } 0 \degree, \text{smaller than } 90\degree.
\text{Right angle}90\degree
\text{Obtuse angle}\text{Larger than } 90\degree, \text{smaller than } 180\degree.
\text{Straight angle}180\degree
\text{Reflex angle}\text{Larger than } 180\degree, \text{smaller than } 360\degree.
\text{Full revolution}360\degree

Whenever two angles share a defining line, ray, or segment, and do not overlap, we say they are adjacent angles . Here are some examples:

Whenever two segments, lines, or rays intersect at a point, two pairs of equal angles are formed. Each angle in the pair is on the opposite side of the intersection point, and they are called vertically opposite angles .

Four angles are formed by the intersecting lines, and there are two pairs of equal angles. Each pair are vertical angles.

If two angles form a right angle, we say they are complementary . We then know that they add to 90\degree .

If two angles form a straight angle, we say they are supplementary . We then know that they add to 180\degree .

Whenever we know that two (or more) angles form a right angle, a straight angle, or a full revolution, we can write an equation that expresses this relationship.

The angles in the diagram below are complementary. What is the value of x ?

Complementary angles are two angles forming a right angle equivalent to 90\degree .

\displaystyle x + 39\displaystyle =\displaystyle 90Equate the sum of the angles to 90
\displaystyle x\displaystyle =\displaystyle 51Subtract 39 from both sides

We never use degrees once we are working with an equation. We are solving for the value of x , and we don't want to double up on using the degree symbol.

Adjacent angles are two angles sharing a defining line, ray, or segment, and do not overlap.

Vertical angles are two pairs of equal angles formed whenever two segments, lines, or rays intersect at a point.

If two angles form a right angle, we say they are complementary.

If two angles form a straight angle, we say they are supplementary.

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COMMENTS

  1. Missing Angles Practice Questions

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  2. Angles and parallel lines : Year 7: Planning tool

    solve problems using the properties of angles, parallel lines and the interior angle sum; ... By the end of Year 7, students can apply knowledge of angle relationships and the sum of angles in a triangle to solve problems and apply this to other shapes and the size of unknown angles. Students can explain their thinking and reasons.

  3. Finding missing angles (practice)

    180 ∘ 35 ∘ x ∘. x = ∘. 3:00. 8:31. Report a problem. Learn for free about math, art, computer programming, economics, physics, chemistry, biology, medicine, finance, history, and more. Khan Academy is a nonprofit with the mission of providing a free, world-class education for anyone, anywhere.

  4. Part 4: Angle Relationships

    NSW Stage 4 Syllabus Outline. Syllabus. Explanation. Demonstrate that the angle sum of a triangle is 180 o and use this to find the angle sum of a quadrilateral (ACMMG166) This means that you will know how to identify and figure out angle sizes in supplementary angles. Establish properties of quadrilaterals using congruent triangles and angle ...

  5. 7th Grade Angles Worksheets

    7th grade angles worksheets are perfect for students to learn and practice various problems about different angle topics. These worksheets are a great resource for students who wish to expand and improve their skills in angles. These 7th grade math worksheets consist of concepts like naming angles, classifying angles, measuring angles using a ...

  6. Year 7. Lines & Angles

    Worked Example. 1.) Let's try to estimate the size of these two angles: 2.) Draw five different angles in your book, measure them and make a private note of their measurement, then ask your friend to measure them and check to see how accurate she is. Angles larger than 360º. With angles larger than 360º, which we call reflex angles, it is ...

  7. Angles Year 7 Knowledge Organiser And Questions

    Our angles Year 7 knowledge organiser and questions will lend just the helping hand that children need for this complex topic. It's a useful revision tool, too, that will prepare children for testing down the road. ... For more problem-solving, take a look at these Angle Properties Diagram Dilemmas Worksheets! They'd work well in ...

  8. KS3 Angles (MEP

    pdf, 93.91 KB pdf, 25.68 KB pdf, 28.68 KB pdf, 11.96 KB pdf, 50.65 KB pdf, 7.39 KB pdf, 24.1 KB pdf, 20.86 KB pdf, 31.14 KB pdf, 12.64 KB Maths worksheets and activities. The topic of Angles from the Year 7 book of the Mathematics Enhancement Program.

  9. Angles in Parallel Lines

    Down below are the most commonly recognised types of angles: Acute Angle - An angle between 0° to 90. Reflex Angle - An angle greater than 180° but less than 360°. Right Angle - An angle that is exactly 90°. Straight Angle - An angle that is exactly 180°. Full Rotation Angle - An angle of exactly 360°. Obtuse Angle - An angle ...

  10. Angles Knowledge Organiser And Questions

    Angles in a triangle add to 180°. Angles in a quadrilateral add to 360°. Angles on parallel lines: Corresponding angles are equal. Alternate angles are equal. Co-interior angles add to 180°. Angles in polygons (where n is the number of sides): Total interior angles of any polygon. = ( n - 2) × 180.

  11. Angles in Parallel Lines

    The worksheet requires learners to demonstrate their understanding of angles in parallel lines, triangles, and quadrilaterals. Your students must use their knowledge to find all the missing angles on the worksheet. Ideal for use alongside taught content or for consolidation purposes as independent work, this Year 7 angles worksheet is an ...

  12. Angles Test

    Year 7 (Yr 8 NZ, KS 2/3) Year 7 Topics; Year 7 Quiz; Year 7 Investigations; Angles. Summary; Test; FAQ; Exercise; ... History of Maths; Number Facts; Acknowledgements; Glossary; Regular Features. Interesting Numbers; Problem Solving; Numbers in the News; Joker's Corner; Strange but True; Angles Test. Navigation. Home; Year 7 (Yr 8 NZ, KS 2/3 ...

  13. Free Printable Angles Worksheets for 7th Year

    Angles worksheets for Year 7 are an essential resource for teachers looking to enhance their students' understanding of math and geometry concepts. These worksheets provide a variety of exercises and problems that challenge students to apply their knowledge of angles, lines, and shapes in a practical and engaging manner.

  14. PDF Year 7 Angles Study Notes

    Year 7 Mathematics Angles Study Notes NAMING AN ANGLE This angle can is named ∠ABC or ∠CBA or ∠B When naming an angle the vertex letter must be the centre letter TYPES OF ANGLES Acute angle - less than 90° Right angle - Exactly 90° Obtuse angle - Between 90° and 180°

  15. IXL

    Fun maths practice! Improve your skills with free problems in 'Types of angles' and thousands of other practice lessons.

  16. Free Math 7 Worksheets

    Find the missing angle for the intersecting lines, worksheet #2. Find the missing angle in the triangles and the covex quadrilaterals, worksheet #1. Find the missing angle in the triangles and the covex quadrilaterals, worksheet #2. Find the missing angle in the triangles and the covex quadrilaterals, worksheet #3.

  17. Angles Questions (Angles Questions with Solutions)

    Linear pair of angles: Sum of angles = 180°. Sum of angles at a point = 360°. 3. Find the measure of an angle which is complementary to 33°. Solution: If the sum of two angles is 90°, they are called complementary angles. Let x be the angle which is complementary to 33°. So, x + 33° = 90°. x = 90° - 33° = 57°.

  18. Angles in Polygons Practice Questions

    Click here for Answers. . missing, polygon, angle. Practice Questions. Previous: Angles in Parallel Lines Practice Questions. Next: Arc Length Practice Questions. The Corbettmaths Practice Questions on Angles in Polygons.

  19. IXL

    Name, measure and classify angles. IXL's SmartScore is a dynamic measure of progress towards mastery, rather than a percentage grade. It tracks your skill level as you tackle progressively more difficult questions. Consistently answer questions correctly to reach excellence (90), or conquer the Challenge Zone to achieve mastery (100)!

  20. PDF Year 7 Knowledge Organiser ANGLE PROPERTIES

    Parallel: Two lines. Alternate which never angles are equal. intersect. Marked by an arrow on each line. = 130 as corresponding. = 70 as co-interior angles. Co-interior Transversal: A line angles are equal. angles add to which intersects 180 . n = 50 as angles on a line. add to 180 .

  21. Year 7. Angles in parallel lines

    Exercise 1. Alternate angles. As well as creating corresponding angles, a transversal crossing parallel lines also forms alternate angles. Let's draw some diagrams to identify these. In general the most important thing is that we know when two angles are equal, but we should also know why (i.e. if it is because they are corresponding ...

  22. 9.02 Measuring angles

    Free lesson on Measuring angles, taken from the 9 Angles, lines, and shapes topic of our Australian Curriculum 3-10a 2020/21 Editions Year 7 textbook. Learn with worked examples, get interactive applets, and watch instructional videos. Book a Demo. Topics. 9 A n g l e s, l i n e s, a n d s h a p e s. 9. 0 1 G e o m e t r i c a l d i a g r a m s.

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    4 Times Tables - Multiplication Word Problems 1 review. Explore more than 7,303 "Angles Problem Solving" resources for teachers, parents and pupils as well as related resources on "Angles". Check out our interactive series of lesson plans, worksheets, PowerPoints and assessment tools today! All teacher-made, aligned with the Australian Curriculum.