Year 9 Angles in Polygons Worksheet — Level 2 — Practice Set 4 — Answers
Answer sheet with worked solutions for the Year 9 angles worksheet.
Success TutoringWorksheetsAnswer sheetYear 9 · Mathematics · AnglesYear 9 Angles in Polygons Worksheet — Level 2 — Practice Set 4 — 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 dodecagon.
Answer: 1,800°
- Angle sum = (n − 2) × 180°
- (12 − 2) × 180° = 1,800°
2.Find the size of each interior angle of a regular decagon.
Answer: 144°
- Angle sum = (10 − 2) × 180° = 1,440°
- 1,440° ÷ 10 = 144°
3.Find the size of each exterior angle of a regular hexagon.
Answer: 60°
- Exterior angles add to 360°
- 360° ÷ 6 = 60°
4.Each exterior angle of a regular polygon is 18°. How many sides does it have?
Answer: 20
- Exterior angles add to 360°
- 360 ÷ 18 = 20 sides
5.Find the sum of the interior angles of a nonagon.
Answer: 1,260°
- Angle sum = (n − 2) × 180°
- (9 − 2) × 180° = 1,260°
6.Find the size of each interior angle of a regular nonagon.
Answer: 140°
- Angle sum = (9 − 2) × 180° = 1,260°
- 1,260° ÷ 9 = 140°
7.Find the size of each exterior angle of a regular 36-sided polygon.
Answer: 10°
- Exterior angles add to 360°
- 360° ÷ 36 = 10°
8.Each exterior angle of a regular polygon is 60°. How many sides does it have?
Answer: 6
- Exterior angles add to 360°
- 360 ÷ 60 = 6 sides
9.Find the sum of the interior angles of a pentagon.
Answer: 540°
- Angle sum = (n − 2) × 180°
- (5 − 2) × 180° = 540°
10.Find the size of each interior angle of a regular 20-sided polygon.
Answer: 162°
- Angle sum = (20 − 2) × 180° = 3,240°
- 3,240° ÷ 20 = 162°
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