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Area of Circle

Area of Circle - illustration

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
or
Area of Circle = Ludolph's number × radius2

A = (π × d2) / 4 = π × r2

Area of Circle - calculator

2D & 3D CalcCalculator for Area of Circle