Year 8 Angles in Polygons Worksheet — Level 1 — Practice Set 2 — Answers
Answer sheet with worked solutions for the Year 8 angles worksheet.
Success TutoringWorksheetsAnswer sheetYear 8 · Mathematics · AnglesYear 8 Angles in Polygons Worksheet — Level 1 — 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°
- Angle sum = (n − 2) × 180°
- (5 − 2) × 180° = 540°
2.Find the size of each interior angle of a regular octagon.
Answer: 135°
- Angle sum = (8 − 2) × 180° = 1,080°
- 1,080° ÷ 8 = 135°
3.Find the sum of the interior angles of a decagon.
Answer: 1,440°
- Angle sum = (n − 2) × 180°
- (10 − 2) × 180° = 1,440°
4.Find the size of each interior angle of a regular pentagon.
Answer: 108°
- Angle sum = (5 − 2) × 180° = 540°
- 540° ÷ 5 = 108°
5.Find the sum of the interior angles of a hexagon.
Answer: 720°
- Angle sum = (n − 2) × 180°
- (6 − 2) × 180° = 720°
6.Find the size of each interior angle of a regular triangle.
Answer: 60°
- Angle sum = (3 − 2) × 180° = 180°
- 180° ÷ 3 = 60°
7.Find the sum of the interior angles of a 20-sided polygon.
Answer: 3,240°
- Angle sum = (n − 2) × 180°
- (20 − 2) × 180° = 3,240°
8.Find the size of each interior angle of a regular dodecagon.
Answer: 150°
- Angle sum = (12 − 2) × 180° = 1,800°
- 1,800° ÷ 12 = 150°
9.Find the sum of the interior angles of a dodecagon.
Answer: 1,800°
- Angle sum = (n − 2) × 180°
- (12 − 2) × 180° = 1,800°
10.Find the size of each interior angle of a regular decagon.
Answer: 144°
- Angle sum = (10 − 2) × 180° = 1,440°
- 1,440° ÷ 10 = 144°
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