How to work out this algebra one problem

Question

Solve for r. Assume this a positive real number

S=4πr2

Answer 1

These used to confuse me, too. We're just gonna do algebra!

We need to divide both sides by 4π.

s/4π = r²

Now, what's the OPPOSITE of squaring a number? Taking the square root. (√25)² = 5² = 25, right?

r = √(s/4π )

If we take the square root of a fraction, we take the square root of the top and the bottom.

r = (1/2)√(s/π)