Geometry Practice Test 3

Ratio between number of sides of two regular polygon = 1 : 2 ⇒ 1x : 2x
Interior angle of the first Polygon = 120°
Interior + Exterior = 180°
I + E = 180°
E = 180° - 20° = 60°
Number of sides in the first Polygon
= $\frac{360°}{60°}$ = 6 side
Number of sides 1x: 2x
6 :12
Number of sides in the second polygon = 12 sides
Exterior angle = $\frac{360°}{\mathrm{number}\mathrm{of}\mathrm{sides}}$
30° = $\frac{360°}{12}$ = 30°
Interior angle = 180° - Exterior angle
= 180° - 30°
Interior angle of the second polygon = 150°