Expert: Bobby Soltani - 1/5/2012

Question
If you have the area of a circle how would you find the diameter?

Answer
The area of a circle is pi times its radius squared, or A = pi*(r)^2.  The radius of a circle is one half of the length of its diameter, or r = (1/2)*d.  Solving the first equation for r, we get

r^2 = A/pi

or

r = SQRT (A/pi)

Since r = (1/2)*d, we can write the equation above as

(1/2)*d = SQRT (A/pi)

multiplying both sides by 2, we get

d = 2*SQRT (A/pi)