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

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

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

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

1.Find the sum of the interior angles of a pentagon.

Answer: 540°

  1. Angle sum = (n − 2) × 180°
  2. (5 − 2) × 180° = 540°
2.Find the size of each interior angle of a regular 30-sided polygon.

Answer: 168°

  1. Angle sum = (30 − 2) × 180° = 5,040°
  2. 5,040° ÷ 30 = 168°
3.Find the size of each exterior angle of a regular quadrilateral.

Answer: 90°

  1. Exterior angles add to 360°
  2. 360° ÷ 4 = 90°
4.Each exterior angle of a regular polygon is 30°. How many sides does it have?

Answer: 12

  1. Exterior angles add to 360°
  2. 360 ÷ 30 = 12 sides
5.Find the sum of the interior angles of a dodecagon.

Answer: 1,800°

  1. Angle sum = (n − 2) × 180°
  2. (12 − 2) × 180° = 1,800°
6.Find the size of each interior angle of a regular pentagon.

Answer: 108°

  1. Angle sum = (5 − 2) × 180° = 540°
  2. 540° ÷ 5 = 108°
7.Find the size of each exterior angle of a regular 18-sided polygon.

Answer: 20°

  1. Exterior angles add to 360°
  2. 360° ÷ 18 = 20°
8.Each exterior angle of a regular polygon is 24°. How many sides does it have?

Answer: 15

  1. Exterior angles add to 360°
  2. 360 ÷ 24 = 15 sides
9.Find the sum of the interior angles of a 11-sided polygon.

Answer: 1,620°

  1. Angle sum = (n − 2) × 180°
  2. (11 − 2) × 180° = 1,620°
10.Find the size of each interior angle of a regular nonagon.

Answer: 140°

  1. Angle sum = (9 − 2) × 180° = 1,260°
  2. 1,260° ÷ 9 = 140°
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