Question

The sum of three side quad measures of exterior angles

Answer 1

Since you are extending a side of the polygon, that exterior angle must necessarily be supplementary to the polygon's interior angle. Together, the adjacent interior and exterior angles will add to 180° . For our equilateral triangle, the exterior angle of any vertex is 120° . For a square, the exterior angle is 90° .

Answer 2

The sum of the exterior angles of a regular polygon will always equal 360 degrees.