Question

porter, karon
25-26 div final exam hs geom
if the measure of an exterior angle of a regular polygon is 20°, how many sides does the polygon have?
9
15
10
18

Explanation:

Step1: Recall exterior angle sum rule

The sum of exterior angles of any polygon is $360^\circ$. For a regular polygon, all exterior angles are equal.

Step2: Calculate number of sides

Let $n$ = number of sides. Use formula $n = \frac{360^\circ}{\text{measure of one exterior angle}}$.
Substitute the given exterior angle measure:
$n = \frac{360}{20}$

Answer:

D. 18