Question

what expression could be used to calculate one interior angle of a 13 - gon?
$\frac{(13 - 2)180}{13}$
$(11 - 2)180$
$(13 - 2)180$
not enough information. we must know if the polygon is regular to proceed.

Explanation:

Step1: Recall sum - of - interior - angles formula

The sum of the interior angles of an $n$-gon is given by $(n - 2)\times180^{\circ}$, where $n$ is the number of sides of the polygon. For a 13 - gon, $n = 13$, so the sum of the interior angles is $(13 - 2)\times180$.

Step2: Find one interior angle

To find the measure of one interior angle of a regular $n$-gon, we divide the sum of the interior angles by the number of sides $n$. For a 13 - gon, one interior angle is $\frac{(13 - 2)\times180}{13}$.

Answer:

A. $\frac{(13 - 2)180}{13}$