How do you calculate the circumference of a circle if you know the are

C = 2√ (Aπ).

Step-by-step explanation:

The area A = π r^2 where r = radius

and the circumference = 2 π r.

From the formula for the area r = √ (A / π)

So the circumference is found by substituting in C = 2 π r for r:

C = 2 π √ (A / π)

C = 2√ (Aπ).