## Elementary Algebra

Recall that the surface area of a right circular cone is given by: $\pi r^2 + \pi rs$ Since s equals the diameter of the base, we know that s equals $2r$, Thus: $SA = \pi r^2 + \pi r(2r) \\ 192 = r^2 + 2r^2 \\ 192 = 3r^2 \\ r = 8$