10 questions · Form 2 Mathematics Bab 4: Polygon
Find the value of an exterior angle of a regular 15-sided polygon.
Prefer reading to quizzing? All 10 questions are listed below with the answer and explanation under each one.
1. Find the value of an exterior angle of a regular 15-sided polygon.
Answer: A
Exterior angle = 360° / 15 = 24°.
2. Calculate the measure of each interior angle of a regular pentagon.
Answer: B
Sum = (5 - 2) × 180° = 540°. Each interior angle = 540° / 5 = 108°.
3. The interior angles of a pentagon are 90°, 110°, 120°, 100°, and x. Find the value of x.
Answer: A
Sum of pentagon angles = (5 - 2) × 180° = 540°. x = 540° - (90° + 110° + 120° + 100°) = 540° - 420° = 120°... Wait, 90+110+120+100 = 420. 540 - 420 = 120°... Ah, correct is 120°.
4. Find the sum of interior angles for a polygon with 12 sides (dodecagon).
Answer: A
(12 - 2) × 180° = 10 × 180° = 1800°.
5. Which of the following polygons CANNOT tessellate regular 2D planes on its own?
Answer: C
Interior angle of a regular pentagon is 108°. Since 360° is not divisible by 108°, it leaves gaps/overlaps and cannot tessellate alone.
6. What is the sum of the interior angles of a hexagon (6 sides)?
Answer: C
Formula: (n - 2) × 180°. For n = 6: (6 - 2) × 180° = 4 × 180° = 720°.
7. How many axes of symmetry does a regular decagon have?
Answer: B
For any regular polygon with n sides, the number of axes of symmetry is equal to n. So a decagon has 10 axes of symmetry.
8. What is the sum of the exterior angles of a nonagon (9 sides)?
Answer: A
The sum of the exterior angles of ANY polygon is always 360°.
9. What is the ratio of an interior angle to an exterior angle of a regular hexagon?
Answer: A
For a regular hexagon: Exterior angle = 360° / 6 = 60°. Interior angle = 180° - 60° = 120°. Ratio = 120° : 60° = 2 : 1.
10. Calculate the exterior angle of a regular octagon (8 sides).
Answer: B
Exterior angle of a regular polygon = 360° / n = 360° / 8 = 45°.