Area of a 21 Centimeter Circle
What is the area of a circle with a DIAMETER of 21 cm (radius of 10.5 cm)? How big is a 21 centimeter circle?
Area of a 21cm diameter circle
results may be rounded
Area of a Circle Formula
The area of a circle is pi times the square of its radius. The radius is half the diameter.
Area = π * (Diameter / 2)2
Diameter of a Circle
The diameter of a circle is the distance from one edge to the other, passing through the center. It is twice the radius.