Find the circumference and area of a circle with diameter of 21 inches

To solve for the circumference and the area of a circle, first you must determine the radius.

D = 21 inches

R = 1/2D = 1/2 (21) = 10.5 inches.

C = 2pi • r

C = 2 (3.14) • 10.5 inches

C = 65.97 inches.

A = Pi • r ^2

A = (3.14) • 10.5^2

A = 346.185 in^2.

The area of a circle is 346.185 in^2.