In a shape with straight sides, such as a rectangle, the distance around the shape is called the The distance around a circle is called the circumference.
To find the circumference of a circle, you usually need to know the radius or diameter of the circle. The radius is the distance from the center of the circle to any point on the circle. The diameter is the distance from one side of the circle to the other through the center. The diameter is two times as long as the radius.
