How do you get the circumference of a circle knowing the area?

Answer 1

area = π x radius2

⇒ radius = √(area ÷ π)

circumference = 2π x radius

⇒ circumference = 2π x √(area ÷ π)

⇒ circumference = √(4π2 x area ÷ π)

⇒ circumference = √(4π x area)

So knowing the area, the circumference can be calculated by taking the square root of the area multiplied by 4 times π

Example: What is the circumference of a circle with area 78.54cm2

Circumference = √(4π x area) = √(4π x 78.54cm2) ~= 31.42cm