Question

If the surface area of a sphere is 616 sq cm, find its radius.

Answer 1

Radius of sphere (r) =?
Surface area of sphere = 616 sq cm
Surface area of a sphere = 4πr²
$$\begin{gathered} \Rightarrow 616=4\times \frac{22}{7}\times r^2 \\ \Rightarrow r^2=\frac{616\times 7}{4\times 22} \\ \Rightarrow r^2=49 \\ \Rightarrow r=7\mathrm{cm} \end{gathered}$$