Question

The sum of the interior angles, s, in an n-sided polygon can be determined using the formula s=180(n−2), where n is the number of sides.

Using this formula, how many sides does a polygon have if the sum of the interior angles is 1,260°? Round to the nearest whole number.

Answer 1

Use s = 180(n − 2). Solve for n:
n = s/180 + 2 = 1260/180 + 2 = 7 + 2 = 9.

So the polygon has 9 sides (a nonagon).