Measure the diameter in centimeters. For this example, let the diameter measure 10 cm. Multiply the diameter's length to itself to square it — 10 cm multiplied by 10 cm results in 100 cm^2. Multiply the squared diameter by pi — 100 cm^2 multiplied by pi equals approximately 314.2 cm^...
center is called the radius of a circle. diameter of a circle the diameter of a circle is the length of the line starting from one point on a circle to another point and passing through the center of the circle. it is equal to twice the radius of the circle. it is usually denoted ...