Solution.

The central angle made by the side of a regular polygon of 15 sides
inscribed in a circle = (360

^{0}÷ 15) = 24^{0}
In the figure AB is one of the sides of the regular polygon.

∆ OAB is one of the 15 congruent triangles
made by the regular polygon.

Radius of the circle (r) = OA = 4 cm

**The area of the regular polygon of 15 sides is 48.84 cm2**