Year 9 Angles in Polygons Worksheet — Level 2 — 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 — 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 an octagon.
Answer: 1,080°
- Angle sum = (n − 2) × 180°
- (8 − 2) × 180° = 1,080°
2.Find the size of each interior angle of a regular 15-sided polygon.
Answer: 156°
- Angle sum = (15 − 2) × 180° = 2,340°
- 2,340° ÷ 15 = 156°
3.Find the size of each exterior angle of a regular triangle.
Answer: 120°
- Exterior angles add to 360°
- 360° ÷ 3 = 120°
4.Each exterior angle of a regular polygon is 40°. How many sides does it have?
Answer: 9
- Exterior angles add to 360°
- 360 ÷ 40 = 9 sides
5.Find the sum of the interior angles of a quadrilateral.
Answer: 360°
- Angle sum = (n − 2) × 180°
- (4 − 2) × 180° = 360°
6.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°
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 90°. How many sides does it have?
Answer: 4
- Exterior angles add to 360°
- 360 ÷ 90 = 4 sides
9.Find the sum of the interior angles of a 14-sided polygon.
Answer: 2,160°
- Angle sum = (n − 2) × 180°
- (14 − 2) × 180° = 2,160°
10.Find the size of each interior angle of a regular hexagon.
Answer: 120°
- Angle sum = (6 − 2) × 180° = 720°
- 720° ÷ 6 = 120°
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