Circumference = πdIn the circle above, the radius is 3, so the circumference is 2π(3) = 6π.
FOUR CIRCLE FORMULAS
Circumference = 2πr = πdLength of an Area of a Circle = πr^2Area of a Length of an arc: An arc is a piece of the circumference. If n is the degree
measure of the arc’s central angle, then the formula is: