__Area of a Regular polygon of n sides when the radius r of the inscribed circle is given__**:**

Since

Area of the polygon area of the

But ,

and

Hence, area of the regular polygon

Also, perimeter of the polygon

(Putting for from above)

__Example__:

A regular octagon circumscribed a circle of radius. Find the area of the octagon.

__Solution__:

Here ,

Area of the polygon

Area of the polygon Square meter approx.