This is a regular pentagon, as all sides are of equal length.

AB = BC = CD = DE = EA

The sum of interior angles of pentagon is

= (n – 2) × 180° [n is number of sides of polygon)]

= (5 – 2) X 180°

= 540°

Since, it is a regular pentagon. It’s all interior angle will be equal.

Size of Interior Angle x = 540/5

= 108°