Area Circumference Diameter Radius pei

The formulas for calculating the area, circumference, diameter, and radius of a circle are as follows:

Area = πr^2
Circumference = 2πr
Diameter = 2r
Radius = The distance from the center of the circle to any point on its circumference.

In these formulas, π is a constant approximately equal to 3.14159 and r represents the radius of the circle.