Area of a circle is calculated following the formula:
A = Π × r2
Where A = area of the circle, Π = Pi (Pi = 3.14; more about Pi below), and r = radius of the circle
If the radius of a circle is 3 units then the area of the circle will be:
A = 3.14 × 32 = 3.14 × 9 = 28.26 square units
Π (Pi) - is a Greek letter used in Geometry to represent the ratio of the circumference of a circle to the diameter.