Area of Circle
The area of a circle is an area, which is bounded by a circular line. For example, a circular garden that has a fence around it. The area of the garden is like the area of a circle and the length of a fence is like a circumference of a circle.
To calculate the area of a circle, we need to know its radius or diameter and the pi number (Ludolph's number), its value is 3,141592... In a circle, the diameter is d = 2 × radius "r". The elementary unit of the area is one square metre, it means the second power of one metre (1 m2).
d=2 × r, also r = d / 2
Area of Circle - formula
Area of Circle = (Ludolph's number × diameter2)/4
Area of Circle = Ludolph's number × radius2
A = (π × d2) / 4 = π × r2