## Frustum of a cone

The area of the lateral surface of a frustum of a cone can be calculated in the following two ways:**If the length of the lateral surface is given:**

A = area of the lateral surface

r_{1} = radius of the small circular end plane

r_{2} = radius of the big circular end plane

a = length of the lateral surface**If the height of the frustum is given:**

A = area of the lateral surface

r_{1} = radius of the small circular end plane

r_{2} = radius of the big circular end plane

h = height of the frustum