A circle is a two-dimensional line that forms a closed loop, where every point on that loop is an equal distance from the center.[1] The circumference (C) of a circle is its perimeter, or the distance around it.[2] The area (A) of a circle is how much space the circle takes up or the region enclosed by the circle.[3] Both area and perimeter can be calculated with simple formulas using the radius or diameter of the circle and the value of pi.
