Question 189850
{{{A=pi*r^2}}} Start with the area of a circle formula



{{{16*pi=pi*r^2}}} Plug in the given area {{{A=16pi}}}



{{{(16*cross(pi))/cross(pi)=(cross(pi)*r^2)/cross(pi)}}} Divide both sides by {{{pi}}} (which cancels out)



{{{16=r^2}}} Simplify



{{{4=r}}} Take the square root of both sides (we're only considering the positive square root)



{{{r=4}}} Rearrange the terms.



So the radius is 4 feet