### Home > CCG > Chapter 7 > Lesson 7.2.1 > Problem7-55

7-55.

Jamal used a hinged mirror to create a regular polygon like you did in Lesson 7.1.4.

1. If his hinged mirror formed a $72°$ angle and the core region in front of the mirror was isosceles, how many sides did his polygon have?

Use the formula: $\frac{360°}{°\text{of each angle}}=\text{Number of sides}$

$5\; \text{sides}$

2. Now Jamal has decided to create a regular polygon with $9$ sides, called a nonagon. If his core region is again isosceles, what angle is formed by his mirror?

Use the formula given in hint (a) and solve for the unknown piece.