To calculate the area of a circle, you need to use the number π (pi) and the radius of the circle (r). The area of the circle (A) is calculated as the square of the radius multiplied by π. In mathematical terms this is,

A =

^{πr2}

is shown in the form Here π (pi) is taken as approximately 3.14159. If the diameter of the circle (d) is known, the radius is found to be half the diameter, i.e;

r = d/2

For example, if you want to calculate the area of a circle with a radius of 5 cm, you would use the formula as follows:

A = π x (5

^{)2}

The area of this circle, if we take the value of π to be 3.14, is approximately 78.5 cm².