Free Grade 3 Angles in Polygons in Context Flashcards
Free Grade 3 flashcards for Angles in Polygons in Context: 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°.
Free
Foundation
35 min
24
Learning objectives
Every objective is checkable, and each one maps to an activity and an assessment.
- UnderstandExplain angles in polygons in context
Explain angles in polygons in context accurately in a familiar context.
Assessed by: Exit ticket of four short items
- ApplyCalculate angles in polygons in context
Calculate angles in polygons in context accurately in a familiar context.
Assessed by: Exit ticket of four short items
- AnalyseCompare angles in polygons in context
Compare angles in polygons in context accurately in a familiar context.
Assessed by: Exit ticket of four short items
- EvaluateJustify angles in polygons in context
Justify angles in polygons in context 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 Angles in Polygons in Context 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°.
12 practice questions
Easy to hard, 24 marks in total. Try them first, then open the answers.
- 1.Two angles on a straight line. One is 32°. Find the other.[1]
- 2.Two angles on a straight line. One is 62°. Find the other.[1]
- 3.Two angles on a straight line. One is 29°. Find the other.[1]
- 4.Two angles on a straight line. One is 124°. Find the other.[1]
- 5.A triangle has angles 80° and 65°. Find the third angle.[2]
- 6.A triangle has angles 78° and 61°. Find the third angle.[2]
- 7.A triangle has angles 79° and 74°. Find the third angle.[2]
- 8.A triangle has angles 39° and 29°. Find the third angle.[2]
- 9.Find the size of each interior angle of a regular 6-sided polygon.[3]
- 10.Find the size of each interior angle of a regular 7-sided polygon.[3]
- 11.Find the size of each interior angle of a regular 5-sided polygon.[3]
- 12.Find the size of each interior angle of a regular 8-sided polygon.[3]
Show answers and working
1. 148°
Angles on a straight line add to 180°. 180 − 32 = 148°.
2. 118°
Angles on a straight line add to 180°. 180 − 62 = 118°.
3. 151°
Angles on a straight line add to 180°. 180 − 29 = 151°.
4. 56°
Angles on a straight line add to 180°. 180 − 124 = 56°.
5. 35°
Angles in a triangle add to 180°. 180 − 80 − 65 = 35°.
6. 41°
Angles in a triangle add to 180°. 180 − 78 − 61 = 41°.
7. 27°
Angles in a triangle add to 180°. 180 − 79 − 74 = 27°.
8. 112°
Angles in a triangle add to 180°. 180 − 39 − 29 = 112°.
9. 120°
Sum of interior angles = (6 − 2) × 180 = 720°. Each angle = 720 ÷ 6 = 120°.
10. 128.57°
Sum of interior angles = (7 − 2) × 180 = 900°. Each angle = 900 ÷ 7 = 128.57°.
11. 108°
Sum of interior angles = (5 − 2) × 180 = 540°. Each angle = 540 ÷ 5 = 108°.
12. 135°
Sum of interior angles = (8 − 2) × 180 = 1080°. Each angle = 1080 ÷ 8 = 135°.
Worked examples
Two angles on a straight line. One is 87°. Find the other.
- Angles on a straight line add to 180°.
- 180 − 87 = 93°.
- Answer: 93°
A triangle has angles 38° and 44°. Find the third angle.
- Angles in a triangle add to 180°.
- 180 − 38 − 44 = 98°.
- Answer: 98°
Find the size of each interior angle of a regular 10-sided polygon.
- Sum of interior angles = (10 − 2) × 180 = 1440°.
- Each angle = 1440 ÷ 10 = 144°.
- Answer: 144°
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.
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Frequently asked
- Is this Grade 3 Angles in Polygons in Context flashcards really free?
- Yes. Every flashcards on FreeMathWorksheet is free to use, print and share — no account, no paywall and no watermark.
- What should a learner already know before this?
- Start with Working with Angles in Polygons, Introducing Angles in Polygons, Angles in Parallel Lines. Each one has its own free lesson, worksheet and quiz.
- How is the flashcards 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 Angles in Polygons in Context?
- Move on to Angles on a Straight Line, Angles Around a Point, Vertically Opposite Angles, Angles in Parallel Lines, which build directly on this idea.
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