If I know the area of a circle I know that I can find the circumference of the circle by the formula C=Sqrt(4 Pi A) where A is the area of the given circle. My question is where does this formula come from? Thank you.

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- Mar 23rd 2008, 10:15 AMschinb64Circumference to area
If I know the area of a circle I know that I can find the circumference of the circle by the formula C=Sqrt(4 Pi A) where A is the area of the given circle. My question is where does this formula come from? Thank you.

- Mar 23rd 2008, 10:46 AMbobak

using we have

you put this into the formula for the circumference.

bring the into the root.

cancel down to get