To measure the circumference of a circle, first measure the diameter and multiply that number by the mathematical constant pi. The diameter is a straight line that goes from one side of the circle to the other and passes... More »

The circumference of a circle is the distance around the outskirts of the circle. Knowing the radius of any circle allows one to calculate its circumference. More »

Find the circumference of a circle using the formula 2 x π x r. You need the value of π, or pi, and the radius of the circle. More » Math Geometry Shapes

To calculate the diameter of a circle, multiply the radius of the circle by 2. Diameter is the measure of the length of a straight line that passes through the center of a circle, touching the circumference or surface at... More » Math Geometry Shapes

To calculate a circle's diameter from its circumference, one should divide the circumference by the constant pi, which is an irrational number approximately equal to 3.14159265358979. More »

To find the arc of a circle, divide the angle subtended at the center of the arc by 360 degrees, then multiply the answer by the circumference of the circle. You need to know the value of pi and must have a protractor to... More »

If the circumference or the area of a circle is known, pi can be used to find the diameter and the radius of that circle. Likewise, if the radius or diameter is known, pi can be used to find out the circumference or the ... More »