First you have to write down the formula on how to get the circumference of the circle (C = 2pi * Radius) and the Area of the circle which is (A=Pi*Radius^2). In getting the radius you need to transform the formula of the circumference by making the radius to be the unknown variable so it would become(R=C/2pi), after that you need to replace the radius in the formula of the area by the transformed formula of the circumference and you will come up of the formula of (A=Pi(C/2pi)^2).
