A=pie×radius squared is the area formula of a circle. The circumference formula or a circle is C=pie×diameter. 615.75=(3.14)(radius) squared. Divide both sides by the 3.14. What ever 615.75 divided by 3.14 is-is radius squared. The square root is your radius. The radius is half the diameter, so double what you have right now as the radius to get the diameter. Now since C=pie×diameter, your circumference is your pie×your diameter. Whatever your answer is-is your circumference.
