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Year 8 Angles in Polygons Worksheet — Level 1 — Practice Set 3 — Answers

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Success TutoringWorksheetsAnswer sheetYear 8 · Mathematics · Angles

Year 8 Angles in Polygons Worksheet — Level 1 — 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 decagon.

Answer: 1,440°

  1. Angle sum = (n − 2) × 180°
  2. (10 − 2) × 180° = 1,440°
2.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°
3.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°
4.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°
5.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°
6.Find the size of each interior angle of a regular decagon.

Answer: 144°

  1. Angle sum = (10 − 2) × 180° = 1,440°
  2. 1,440° ÷ 10 = 144°
7.Find the sum of the interior angles of a 20-sided polygon.

Answer: 3,240°

  1. Angle sum = (n − 2) × 180°
  2. (20 − 2) × 180° = 3,240°
8.Find the size of each interior angle of a regular 18-sided polygon.

Answer: 160°

  1. Angle sum = (18 − 2) × 180° = 2,880°
  2. 2,880° ÷ 18 = 160°
9.Find the sum of the interior angles of a heptagon.

Answer: 900°

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

Answer: 135°

  1. Angle sum = (8 − 2) × 180° = 1,080°
  2. 1,080° ÷ 8 = 135°
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