Answer:
a) interior angle: 156°
b) exterior angle: 24°
Explanation:
b)
The sum of the exterior angles of a convex polygon is 360°. Then the exterior angle of a regular 15-gon will be ...
360°/15 = 24°
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a)
The interior angle of a convex polygon is the supplement of the exterior angle at that vertex. For an exterior angle of 24°, a regular 15-gon will have an interior angle of ...
180° -24° = 156°
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Additional comment
We find it easier to work this problem by finding the exterior angle first. Note that the results only apply to a 15-gon in which all interior angles are congruent.