Question

The surface area of a sphere is $5544c{m}^2$. Find the diameter.

Answer 1

Let r be the radius of a sphere, then surface area $=4\pi r^2$
$5544=4\times \frac{22}{7}\times r^2\Rightarrow r^2=\frac{5544\times 7}{4\times 22}=63\times 7c{m}^2=441=(21{)}^2\therefore r=21cm$
now diameter $=2r=2\times 21=42cm$