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

Answer: 900°

  1. Angle sum = (n − 2) × 180°
  2. (7 − 2) × 180° = 900°
2.Find the size of each interior angle of a regular 24-sided polygon.

Answer: 165°

  1. Angle sum = (24 − 2) × 180° = 3,960°
  2. 3,960° ÷ 24 = 165°
3.Find the size of each exterior angle of a regular octagon.

Answer: 45°

  1. Exterior angles add to 360°
  2. 360° ÷ 8 = 45°
4.Each exterior angle of a regular polygon is 20°. How many sides does it have?

Answer: 18

  1. Exterior angles add to 360°
  2. 360 ÷ 20 = 18 sides
5.Find the sum of the interior angles of a 14-sided polygon.

Answer: 2,160°

  1. Angle sum = (n − 2) × 180°
  2. (14 − 2) × 180° = 2,160°
6.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°
7.Find the size of each exterior angle of a regular quadrilateral.

Answer: 90°

  1. Exterior angles add to 360°
  2. 360° ÷ 4 = 90°
8.Each exterior angle of a regular polygon is 12°. How many sides does it have?

Answer: 30

  1. Exterior angles add to 360°
  2. 360 ÷ 12 = 30 sides
9.Find the sum of the interior angles of a 15-sided polygon.

Answer: 2,340°

  1. Angle sum = (n − 2) × 180°
  2. (15 − 2) × 180° = 2,340°
10.Find the size of each interior angle of a regular dodecagon.

Answer: 150°

  1. Angle sum = (12 − 2) × 180° = 1,800°
  2. 1,800° ÷ 12 = 150°
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