## Elementary Algebra

The total surface area of the sphere is 144$\pi$ $cm^2$.
The diameter is twice the radius So: d = 2r 12 = 2r r = 6 The formula for the surface area of a sphere is 4 $\times$ $\pi$ $\times$ $r^{2}$ Substitute 6 for r to obtain: A = 4 $\times$ $\pi$ $\times$ $6^{2}$ A = 4 $\times$ $\pi$ $\times$ 36 A = 144$\pi$