Circle Formulas

1. Area of Circle Formula

Area = π \times r 2

Area is π times the square of the radius (r).

Circumference = 2 π \times r

Circumference is 2π times the radius (r).

d = 2 r

Diameter (d) is twice the radius (r).

r = \sqrt{\frac{Area}{π}}

Radius is the square root of the area divided by π.

r = \frac{Circumference}{2 π}

Radius is the circumference divided by 2π.