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WAEC Mathematics 2020 Paper

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Question : 27

Total: 48

Each interior angle of a regular polygon is 168

^{\circ}

. Find the number of sides of the polygon

30
36
24
18

Solution:

Concept:

For any regular polygon, the exterior angle is supplementary to the interior angle, and the sum of all exterior angles is

360^\circ

.

Explanation:

Interior angle

= 168^\circ

Exterior angle

= 180^\circ - 168^\circ = 12^\circ

Number of sides

= \frac{360^\circ}{\text{exterior angle}}

Number of sides

= \frac{360^\circ}{12^\circ} = 30

Answer:

The polygon has

30

sides. Option A.

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