Circumference of a Circle
The circumference of a circle is the distance around a circle, also known as
the perimeter of a circle.
Before determining the circumference of a circle, either the radius or the
diameter of the circle must be known.
The radius of a circle is the distance of the center of a circle to any point on
the circumference.
The diameter of a circle is a straight line passing through the center of a
circle that touches both sides of the circumference.