Remember that the formula for the surface area of a sphere is:
[tex]S=4\pi r^2[/tex]If a sphere has a diameter of 20", the radius is 10".
Using this and the formula, we'll get:
[tex]\begin{gathered} S=4\pi(10^2) \\ \rightarrow S=1256.64in^2 \end{gathered}[/tex]
