Question

The volume of a sphere is 38808 cm³. Find its radius and hence its surface area.

Answer 1

Volume of the sphere = 38808 cm³
Suppose that r cm is the radius of the given sphere.

$$\begin{gathered} \therefore \frac{4}{3}\mathrm{\pi }{r}^{\mathit{}\mathit{3}}=38808 \\ \Rightarrow r^{\mathit{3}}=\frac{38808\times 3\times 7}{4\times 22}=9261 \\ \Rightarrow r\mathit{}=\sqrt[3]{9261}=21\mathrm{cm} \end{gathered}$$

∴ Surface area of the sphere =$4\mathrm{\pi }{r}^2$
$$\begin{gathered} =4\times \frac{22}{7}\times 21\times 21 \\ =5544{\mathrm{cm}}^2 \end{gathered}$$