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Free Grade 3 Introducing Vertically Opposite Angles Techniques Lessons

Free Grade 3 lessons for Introducing Vertically Opposite Angles Techniques: 12 real questions with a full answer key and worked solutions. Angles on a straight line add to 180°, around a point to 360°, and inside a triangle to 180°. A polygon with n sides has interior angles adding to (n − 2) × 180°.

Price

Free

Difficulty

Higher

Estimated time

20 min

Total marks

24

Learning objectives

Every objective is checkable, and each one maps to an activity and an assessment.

  • RememberIdentify introducing vertically opposite angles techniques

    Identify introducing vertically opposite angles techniques accurately in a familiar context.

    Assessed by: Exit ticket of four short items

  • UnderstandExplain introducing vertically opposite angles techniques

    Explain introducing vertically opposite angles techniques accurately in a familiar context.

    Assessed by: Exit ticket of four short items

  • ApplyCalculate introducing vertically opposite angles techniques

    Calculate introducing vertically opposite angles techniques accurately in a familiar context.

    Assessed by: Exit ticket of four short items

  • AnalyseCompare introducing vertically opposite angles techniques

    Compare introducing vertically opposite angles techniques accurately in a familiar context.

    Assessed by: Exit ticket of four short items

Prerequisites

Close these gaps first — each has its own free lesson, worksheet and quiz.

Introducing Vertically Opposite Angles Essentials
Angles Around a Point

How Introducing Vertically Opposite Angles Techniques works

Angles on a straight line add to 180°, around a point to 360°, and inside a triangle to 180°. A polygon with n sides has interior angles adding to (n − 2) × 180°.

Key wordsdegreeacuteobtusereflexinterior angle

12 practice questions

Easy to hard, 24 marks in total. Try them first, then open the answers.

  1. 1.Two angles on a straight line. One is 110°. Find the other.[1]
  2. 2.Two angles on a straight line. One is 121°. Find the other.[1]
  3. 3.Two angles on a straight line. One is 34°. Find the other.[1]
  4. 4.Two angles on a straight line. One is 33°. Find the other.[1]
  5. 5.A triangle has angles 47° and 56°. Find the third angle.[2]
  6. 6.A triangle has angles 70° and 69°. Find the third angle.[2]
  7. 7.A triangle has angles 43° and 104°. Find the third angle.[2]
  8. 8.A triangle has angles 49° and 78°. Find the third angle.[2]
  9. 9.Find the size of each interior angle of a regular 8-sided polygon.[3]
  10. 10.Find the size of each interior angle of a regular 7-sided polygon.[3]
  11. 11.Find the size of each interior angle of a regular 5-sided polygon.[3]
  12. 12.Find the size of each interior angle of a regular 6-sided polygon.[3]
Show answers and working

  1. 1. 70°

    Angles on a straight line add to 180°. 180 − 110 = 70°.

  2. 2. 59°

    Angles on a straight line add to 180°. 180 − 121 = 59°.

  3. 3. 146°

    Angles on a straight line add to 180°. 180 − 34 = 146°.

  4. 4. 147°

    Angles on a straight line add to 180°. 180 − 33 = 147°.

  5. 5. 77°

    Angles in a triangle add to 180°. 180 − 47 − 56 = 77°.

  6. 6. 41°

    Angles in a triangle add to 180°. 180 − 70 − 69 = 41°.

  7. 7. 33°

    Angles in a triangle add to 180°. 180 − 43 − 104 = 33°.

  8. 8. 53°

    Angles in a triangle add to 180°. 180 − 49 − 78 = 53°.

  9. 9. 135°

    Sum of interior angles = (8 − 2) × 180 = 1080°. Each angle = 1080 ÷ 8 = 135°.

  10. 10. 128.57°

    Sum of interior angles = (7 − 2) × 180 = 900°. Each angle = 900 ÷ 7 = 128.57°.

  11. 11. 108°

    Sum of interior angles = (5 − 2) × 180 = 540°. Each angle = 540 ÷ 5 = 108°.

  12. 12. 120°

    Sum of interior angles = (6 − 2) × 180 = 720°. Each angle = 720 ÷ 6 = 120°.

Worked examples

Easy example

Two angles on a straight line. One is 106°. Find the other.

  1. Angles on a straight line add to 180°.
  2. 180 − 106 = 74°.
  3. Answer: 74°
Medium example

A triangle has angles 56° and 44°. Find the third angle.

  1. Angles in a triangle add to 180°.
  2. 180 − 56 − 44 = 80°.
  3. Answer: 80°
Hard example

Find the size of each interior angle of a regular 10-sided polygon.

  1. Sum of interior angles = (10 − 2) × 180 = 1440°.
  2. Each angle = 1440 ÷ 10 = 144°.
  3. Answer: 144°

Interactive practice

Free, no account required — answer on screen or print it.

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Common mistakes

What learners typically get wrong, and how to fix it.

  • Reads the wrong scale on a protractor.

    Correction: Start from the 0 on the arm you are measuring from.

  • Uses 360° for a triangle.

    Correction: Triangle = 180°, quadrilateral = 360°.

Teacher tips

  • · Estimate the angle type before measuring.

Parent tips

  • · Spot right angles around the house.

Real-life applications

  • · Ramps, clock hands, building and design.

Assessment objectives

How mastery is evidenced, and which standards it maps to.

COMMON-CORE COM-387.1 — Mapped statement covering Introducing Vertically Opposite Angles Techniques.OCR OCR-278.2 — Mapped statement covering Introducing Vertically Opposite Angles Techniques.

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Goes deeper

The entities below this one, each with the same complete free resource set.

Introduction to Introducing Vertically Opposite Angles Techniques
Key Vocabulary of Introducing Vertically Opposite Angles Techniques
Rules and Methods in Introducing Vertically Opposite Angles Techniques
Working with Introducing Vertically Opposite Angles Techniques
Introducing Vertically Opposite Angles Techniques in Examinations

Sibling concepts

Introducing Vertically Opposite Angles Essentials
Introducing Vertically Opposite Angles Word Problems
Introducing Vertically Opposite Angles Common Errors

Related concepts

Lateral links, including across subjects.

Introducing Vertically Opposite Angles Essentials
Introducing Vertically Opposite Angles Word Problems
Introducing Vertically Opposite Angles Common Errors
Working with Vertically Opposite Angles

Next topics

Introducing Vertically Opposite Angles Word Problems
Introducing Vertically Opposite Angles Common Errors
Working with Vertically Opposite Angles
Vertically Opposite Angles in Context

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Frequently asked

Is this Grade 3 Introducing Vertically Opposite Angles Techniques lesson really free?
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What should a learner already know before this?
Start with Introducing Vertically Opposite Angles Essentials, Angles Around a Point. Each one has its own free lesson, worksheet and quiz.
How is the lesson sequenced?
Recognition first, then understanding, application, reasoning and finally mastery — the same ladder used across every free resource on the platform.
What comes next after Introducing Vertically Opposite Angles Techniques?
Move on to Introducing Vertically Opposite Angles Word Problems, Introducing Vertically Opposite Angles Common Errors, Working with Vertically Opposite Angles, Vertically Opposite Angles in Context, which build directly on this idea.

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