Answer:
area of base =

where 'r' is the radius
Explanation:
Volume of the cylinder formula =

volume of cylinder = area of base * height
The base of a cylinder is a circle. so we use the area of circle for the base of cylinder while finding volume
We know area of the circle is

So area of the base of cylinder is

To find volume of the cylinder , we multiply the base of the cylinder with height
To determine the base of the cylinder we need radius of the cylinder
area of base =

where 'r' is the radius