Question

Find the surface area of a sphere of diameter $3.5\mathrm{cm}$. Assume $\mathrm{\pi }=\frac{22}{7}$

Answer 1

Step 1: Find radius of sphere

Diameter of sphere, $d=3.5\mathrm{cm}$

Thus, radius of sphere, $r=\frac{d}{2}=\frac{3.5}{2}=1.75\mathrm{cm}$

$\mathrm{\pi }=\frac{22}{7}$

Step 2: Find surface area of sphere

Surface area ($S$) of a sphere is given as,

$S=4{\mathrm{\pi r}}^2$

Thus,

$$\begin{gathered} S=4·\frac{22}{7}·1.{75}^2 \\ =38.5{\mathrm{cm}}^2 \end{gathered}$$

Therefore, the surface area of the sphere of radius $3.5\mathrm{cm}$ is $38{\mathrm{cm}}^2$.