Since the figure is a regular polygon, it is equiangular and equilateral. Since it has four sides, the figure must be a square.
A square is also a quadrilateral; therefore, the sum of its inner angles is equal to 360°. Because a square is a regular polygon each of its angles is 360°/4=90°.
The sum of interior angles is 360°
1 Interior angle: 90°
In general,
[tex]\text{exterior angle of a polygon}=\frac{360\degree}{number\text{ of sides}}[/tex]
Thus, in our case, each exterior angle is equal to 90° and its sum is 4*90°=360°
