The measure of the exterior angle regular polygon is 30 degrees. How many sides does it have?

1 Answer
Feb 28, 2018

12 sides.

Explanation:

By the Exterior Angle Formula, the sum of the exterior angles in any polygon is 360°. Since the polygon is regular, all the angles are congruent. This is very important: if the polygon was not regular, the exterior angles could be 30°, 170°, and 160°!

Anyway, we can name the number of sides s and the number of angles a. Because every polygon has the same number of sides and angles (because they are closed figures with non-intersecting lines), a=s. Since all the angles are congruent, 30a=360, and a=12. Since a=s, s=12, so the polygon has 12 sides. (This polygon has a short name: a dodecagon).