Split any polygon into triangles to find its angle sum — and each angle when it is regular
Change the number of sides with − and +. Watch the triangles, the angle sum, and each angle.
Number of sides (n)
pentagon
Triangles (n − 2)
3
Angle sum
540°
Each angle (regular)
108°
(5 − 2) × 180° = 3 × 180° = 540°