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

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Success TutoringWorksheetsAnswer sheetYear 8 · Mathematics · Angles

Year 8 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 15-sided polygon.

Answer: 2,340°

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

Answer: 120°

  1. Exterior angles add to 360°
  2. 360° ÷ 3 = 120°
4.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
5.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°
6.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°
7.Find the size of each exterior angle of a regular 30-sided polygon.

Answer: 12°

  1. Exterior angles add to 360°
  2. 360° ÷ 30 = 12°
8.Each exterior angle of a regular polygon is 40°. How many sides does it have?

Answer: 9

  1. Exterior angles add to 360°
  2. 360 ÷ 40 = 9 sides
9.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°
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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