Free Grade 3 Introducing Angle Bisector Worksheets
Free Grade 3 worksheets for Introducing Angle Bisector: 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
20 min
24
Learning objectives
Every objective is checkable, and each one maps to an activity and an assessment.
- RememberIdentify introducing angle bisector
Identify introducing angle bisector accurately in a familiar context.
Assessed by: Exit ticket of four short items
- UnderstandExplain introducing angle bisector
Explain introducing angle bisector accurately in a familiar context.
Assessed by: Exit ticket of four short items
- ApplyCalculate introducing angle bisector
Calculate introducing angle bisector accurately in a familiar context.
Assessed by: Exit ticket of four short items
- AnalyseCompare introducing angle bisector
Compare introducing angle bisector 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 Introducing Angle Bisector 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 57°. Find the other.[1]
- 2.Two angles on a straight line. One is 122°. Find the other.[1]
- 3.Two angles on a straight line. One is 27°. Find the other.[1]
- 4.Two angles on a straight line. One is 94°. Find the other.[1]
- 5.A triangle has angles 31° and 58°. Find the third angle.[2]
- 6.A triangle has angles 80° and 23°. Find the third angle.[2]
- 7.A triangle has angles 80° and 51°. Find the third angle.[2]
- 8.A triangle has angles 36° and 37°. Find the third angle.[2]
- 9.Find the size of each interior angle of a regular 5-sided polygon.[3]
- 10.Find the size of each interior angle of a regular 8-sided polygon.[3]
- 11.Find the size of each interior angle of a regular 10-sided polygon.[3]
- 12.Find the size of each interior angle of a regular 9-sided polygon.[3]
Show answers and working
1. 123°
Angles on a straight line add to 180°. 180 − 57 = 123°.
2. 58°
Angles on a straight line add to 180°. 180 − 122 = 58°.
3. 153°
Angles on a straight line add to 180°. 180 − 27 = 153°.
4. 86°
Angles on a straight line add to 180°. 180 − 94 = 86°.
5. 91°
Angles in a triangle add to 180°. 180 − 31 − 58 = 91°.
6. 77°
Angles in a triangle add to 180°. 180 − 80 − 23 = 77°.
7. 49°
Angles in a triangle add to 180°. 180 − 80 − 51 = 49°.
8. 107°
Angles in a triangle add to 180°. 180 − 36 − 37 = 107°.
9. 108°
Sum of interior angles = (5 − 2) × 180 = 540°. Each angle = 540 ÷ 5 = 108°.
10. 135°
Sum of interior angles = (8 − 2) × 180 = 1080°. Each angle = 1080 ÷ 8 = 135°.
11. 144°
Sum of interior angles = (10 − 2) × 180 = 1440°. Each angle = 1440 ÷ 10 = 144°.
12. 140°
Sum of interior angles = (9 − 2) × 180 = 1260°. Each angle = 1260 ÷ 9 = 140°.
Worked examples
Two angles on a straight line. One is 62°. Find the other.
- Angles on a straight line add to 180°.
- 180 − 62 = 118°.
- Answer: 118°
A triangle has angles 57° and 32°. Find the third angle.
- Angles in a triangle add to 180°.
- 180 − 57 − 32 = 91°.
- Answer: 91°
Find the size of each interior angle of a regular 7-sided polygon.
- Sum of interior angles = (7 − 2) × 180 = 900°.
- Each angle = 900 ÷ 7 = 128.57°.
- Answer: 128.57°
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.
Every free resource for Introducing Angle Bisector
One concept, one ecosystem — all of it free.
Goes deeper
The entities below this one, each with the same complete free resource set.
Sibling concepts
Related concepts
Lateral links, including across subjects.
Next topics
All free formats for this concept
Every kind below is a real page, generated from this entity.
Learn — Meet the idea.
Practice — Build fluency.
Revise — Keep it in memory.
Assess — Prove mastery.
Apply — Use it in context.
Teach — Deliver it to a class.
Frequently asked
- Is this Grade 3 Introducing Angle Bisector worksheet really free?
- Yes. Every worksheets 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 Perpendicular Bisector. 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 Introducing Angle Bisector?
- Move on to Working with Angle Bisector, Angle Bisector in Context, Perpendicular Bisector, Loci, which build directly on this idea.
Related resources
Stuck on Introducing Angle Bisector? The AI Tutor already knows this page, its prerequisites and its common mistakes.
Open the free AI Tutor