Success TutoringWorksheets

8th Grade Angles in Polygons Worksheet — Level 3 — Practice Set 2 — Answers

Answer sheet with worked solutions for the 8th Grade angles worksheet.

Download answers PDFPrint answersBack to worksheet
Success TutoringWorksheetsAnswer sheet8th Grade · Mathematics · Angles

8th Grade Angles in Polygons Worksheet — Level 3 — Practice Set 2 — Answers

Interior angle sum = (n − 2) × 180°. The exterior angles of any convex polygon add to 360°.

1.Find the size of each interior angle of a regular 36-sided polygon.

Answer: 170°

  1. Angle sum = (36 − 2) × 180° = 6,120°
  2. 6,120° ÷ 36 = 170°
2.Each exterior angle of a regular polygon is 72°. How many sides does it have?

Answer: 5

  1. Exterior angles add to 360°
  2. 360 ÷ 72 = 5 sides
3.The interior angles of a hexagon are 114°, 165°, 78°, 145°, 151° and x°. Find x.

Answer: 67°

  1. Angle sum = (6 − 2) × 180° = 720°
  2. x = 720 − 114 − 165 − 78 − 145 − 151 = 67
4.Each interior angle of a regular polygon is 170°. How many sides does it have?

Answer: 36

  1. Each exterior angle = 180° − 170° = 10°
  2. 360 ÷ 10 = 36 sides
5.The interior angles of a polygon add up to 900°. How many sides does it have?

Answer: 7

  1. (n − 2) × 180 = 900
  2. n − 2 = 900 ÷ 180 = 5, so n = 7
6.Find the size of each interior angle of a regular 20-sided polygon.

Answer: 162°

  1. Angle sum = (20 − 2) × 180° = 3,240°
  2. 3,240° ÷ 20 = 162°
7.Each exterior angle of a regular polygon is 45°. How many sides does it have?

Answer: 8

  1. Exterior angles add to 360°
  2. 360 ÷ 45 = 8 sides
8.The interior angles of a pentagon are 103°, 117°, 157°, 94° and x°. Find x.

Answer: 69°

  1. Angle sum = (5 − 2) × 180° = 540°
  2. x = 540 − 103 − 117 − 157 − 94 = 69
9.Each interior angle of a regular polygon is 160°. How many sides does it have?

Answer: 18

  1. Each exterior angle = 180° − 160° = 20°
  2. 360 ÷ 20 = 18 sides
10.The interior angles of a polygon add up to 720°. How many sides does it have?

Answer: 6

  1. (n − 2) × 180 = 720
  2. n − 2 = 720 ÷ 180 = 4, so n = 6
Free worksheets at worksheets.successtutoring.com · © Success Tutoring · Free for personal and classroom use

Marking tips

  • Give credit for correct method even when the final answer slips — the working shows where the thinking went right.
  • For open-ended tasks, use the success criteria as a checklist rather than looking for one "right" answer.
  • Celebrate what went well first, then pick one thing to work on next.