1. The sum of the measures of Interior Angles of n-sided polygon = (n-2) × 180°
2. The sum of the measures of Exterior Angles of n-sided polygon = 360°.
If all polygons are regular or equiangular, then:
A. For pentagon n=5 and the sum of Interior Angles of n-sided polygon = (5-2) × 180°=540°. All interior angles have the same measure, then each interior angle has measure 108°. Each exterior angle has measure 360°:5=72°.
B. For n=16, interior angle will have measure (16-2)×180°/16=157.5° and exterior angle will have measure 360°/16=22.5°.
C. For dodecagon n=12 and interior angle will have measure (12-2)×180°/12=150°, exterior angle will have measure 360°/12=30°.
