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Free Grade 3 Working with Angles in Parallel Lines Common Errors Worksheets

Free Grade 3 worksheets for Working with Angles in Parallel Lines Common Errors: 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 working with angles in parallel lines common errors

    Identify working with angles in parallel lines common errors accurately in a familiar context.

    Assessed by: Exit ticket of four short items

  • UnderstandExplain working with angles in parallel lines common errors

    Explain working with angles in parallel lines common errors accurately in a familiar context.

    Assessed by: Exit ticket of four short items

  • ApplyCalculate working with angles in parallel lines common errors

    Calculate working with angles in parallel lines common errors accurately in a familiar context.

    Assessed by: Exit ticket of four short items

  • AnalyseCompare working with angles in parallel lines common errors

    Compare working with angles in parallel lines common errors 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.

How Working with Angles in Parallel Lines Common Errors 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 100°. Find the other.[1]
  2. 2.Two angles on a straight line. One is 154°. Find the other.[1]
  3. 3.Two angles on a straight line. One is 157°. Find the other.[1]
  4. 4.Two angles on a straight line. One is 64°. Find the other.[1]
  5. 5.A triangle has angles 58° and 45°. Find the third angle.[2]
  6. 6.A triangle has angles 24° and 67°. Find the third angle.[2]
  7. 7.A triangle has angles 45° and 51°. Find the third angle.[2]
  8. 8.A triangle has angles 24° and 113°. Find the third angle.[2]
  9. 9.Find the size of each interior angle of a regular 7-sided polygon.[3]
  10. 10.Find the size of each interior angle of a regular 10-sided polygon.[3]
  11. 11.Find the size of each interior angle of a regular 9-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. 80°

    Angles on a straight line add to 180°. 180 − 100 = 80°.

  2. 2. 26°

    Angles on a straight line add to 180°. 180 − 154 = 26°.

  3. 3. 23°

    Angles on a straight line add to 180°. 180 − 157 = 23°.

  4. 4. 116°

    Angles on a straight line add to 180°. 180 − 64 = 116°.

  5. 5. 77°

    Angles in a triangle add to 180°. 180 − 58 − 45 = 77°.

  6. 6. 89°

    Angles in a triangle add to 180°. 180 − 24 − 67 = 89°.

  7. 7. 84°

    Angles in a triangle add to 180°. 180 − 45 − 51 = 84°.

  8. 8. 43°

    Angles in a triangle add to 180°. 180 − 24 − 113 = 43°.

  9. 9. 128.57°

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

  10. 10. 144°

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

  11. 11. 140°

    Sum of interior angles = (9 − 2) × 180 = 1260°. Each angle = 1260 ÷ 9 = 140°.

  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 88°. Find the other.

  1. Angles on a straight line add to 180°.
  2. 180 − 88 = 92°.
  3. Answer: 92°
Medium example

A triangle has angles 53° and 65°. Find the third angle.

  1. Angles in a triangle add to 180°.
  2. 180 − 53 − 65 = 62°.
  3. Answer: 62°
Hard example

Find the size of each interior angle of a regular 8-sided polygon.

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

Interactive practice

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

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.

AQA AQA-577.1 — Mapped statement covering Working with Angles in Parallel Lines Common Errors.FBISE FBI-513.2 — Mapped statement covering Working with Angles in Parallel Lines Common Errors.

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Frequently asked

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What should a learner already know before this?
Start with Working with Angles in Parallel Lines Word Problems, Working with Angles in Parallel Lines Techniques, Introducing Angles in Parallel Lines. Each one has its own free lesson, worksheet and quiz.
How is the worksheet 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 Working with Angles in Parallel Lines Common Errors?
Move on to Introducing Angles in Parallel Lines, Angles in Parallel Lines in Context, which build directly on this idea.

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