Free Grade 3 Angle Bisector in Context Essentials Flashcards
Free Grade 3 flashcards for Angle Bisector in Context Essentials: 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
25 min
24
Learning objectives
Every objective is checkable, and each one maps to an activity and an assessment.
- UnderstandExplain angle bisector in context essentials
Explain angle bisector in context essentials accurately in a familiar context.
Assessed by: Exit ticket of four short items
- ApplyCalculate angle bisector in context essentials
Calculate angle bisector in context essentials accurately in a familiar context.
Assessed by: Exit ticket of four short items
- AnalyseCompare angle bisector in context essentials
Compare angle bisector in context essentials accurately in a familiar context.
Assessed by: Exit ticket of four short items
- EvaluateJustify angle bisector in context essentials
Justify angle bisector in context essentials 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 Angle Bisector in Context Essentials 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 51°. Find the other.[1]
- 2.Two angles on a straight line. One is 43°. Find the other.[1]
- 3.Two angles on a straight line. One is 105°. Find the other.[1]
- 4.Two angles on a straight line. One is 150°. Find the other.[1]
- 5.A triangle has angles 77° and 26°. Find the third angle.[2]
- 6.A triangle has angles 37° and 81°. Find the third angle.[2]
- 7.A triangle has angles 22° and 116°. Find the third angle.[2]
- 8.A triangle has angles 88° and 38°. Find the third angle.[2]
- 9.Find the size of each interior angle of a regular 9-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 8-sided polygon.[3]
- 12.Find the size of each interior angle of a regular 10-sided polygon.[3]
Show answers and working
1. 129°
Angles on a straight line add to 180°. 180 − 51 = 129°.
2. 137°
Angles on a straight line add to 180°. 180 − 43 = 137°.
3. 75°
Angles on a straight line add to 180°. 180 − 105 = 75°.
4. 30°
Angles on a straight line add to 180°. 180 − 150 = 30°.
5. 77°
Angles in a triangle add to 180°. 180 − 77 − 26 = 77°.
6. 62°
Angles in a triangle add to 180°. 180 − 37 − 81 = 62°.
7. 42°
Angles in a triangle add to 180°. 180 − 22 − 116 = 42°.
8. 54°
Angles in a triangle add to 180°. 180 − 88 − 38 = 54°.
9. 140°
Sum of interior angles = (9 − 2) × 180 = 1260°. Each angle = 1260 ÷ 9 = 140°.
10. 128.57°
Sum of interior angles = (7 − 2) × 180 = 900°. Each angle = 900 ÷ 7 = 128.57°.
11. 135°
Sum of interior angles = (8 − 2) × 180 = 1080°. Each angle = 1080 ÷ 8 = 135°.
12. 144°
Sum of interior angles = (10 − 2) × 180 = 1440°. Each angle = 1440 ÷ 10 = 144°.
Worked examples
Two angles on a straight line. One is 27°. Find the other.
- Angles on a straight line add to 180°.
- 180 − 27 = 153°.
- Answer: 153°
A triangle has angles 37° and 23°. Find the third angle.
- Angles in a triangle add to 180°.
- 180 − 37 − 23 = 120°.
- Answer: 120°
Find the size of each interior angle of a regular 5-sided polygon.
- Sum of interior angles = (5 − 2) × 180 = 540°.
- Each angle = 540 ÷ 5 = 108°.
- Answer: 108°
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
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- What should a learner already know before this?
- Start with Working with Angle Bisector. 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 Angle Bisector in Context Essentials?
- Move on to Angle Bisector in Context Techniques, Angle Bisector in Context Word Problems, Angle Bisector in Context Common Errors, Introducing Angle Bisector, which build directly on this idea.
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