well, the area of a circle = \(\pi\)\(r^{2}\)
so 36 pi = r^2 pi
the pi's cancel and you're left with 36 = r^2
square root both sides to get \(\sqrt{36}\) = r
and r = + or - 6
However, a circle cannot have a negative radius so r = 6 and only a circle with a radius of 6 has an area of 36 pi
To answer your question briefly, there is one circle with an area of 36 pi
