Question

What's the subject formula?​

Answer 1

r = √(A/4π)

Explanation:

A = 4πr^2

Divide both sides by 4π

r^2 = A/4π

Take square root of both sides.

r = √(A/4π)

We take the positive square root only as r must be positive.

Answer 2

r = √A/4π

Explanation:

`A=4\pi r^2\\(A)/(4\pi )=r^2\\\sqrt{(A)/(4\pi ) }=r`