Question

if the great circle circumference of a sphere is 16 pi yards, find its surface area.

Answer 1

$\text{Circumference of a sphere = 16}\pi$$\text{Surface area of a sphere = 4}\pi r^2$$\begin{gathered} \text{Circumference = 16}\pi \\ Fi\text{ nd the radius r from the circumference} \\ 2\pi r\text{ = 16}\pi \\ \text{Divide through by 2}\pi. \\ \frac{2\pi r}{2\pi}\text{ = }\frac{16\pi}{2\pi} \\ r\text{ = 8} \end{gathered}$

Next, find the surface area.

$\begin{gathered} \text{Surface area = 4}\pi r^2 \\ \text{ = 4}\pi\text{ }\times8^2 \\ \text{ = 4}\pi\text{ x 64} \\ \text{ = 256}\pi yd^2 \end{gathered}$