Question

The height of a cone is $15$cm. If its volume is $1570$ cm${}^3$, find the radius of the base.

Answer 1

$h=15$cm, volume $=1570$cm${}^3$

Let radius be $r$
$1570=\frac{1}{3}\times 3.14\times r^2\times 15$
$r=\sqrt{\frac{1570}{15}\times \frac{3}{3.14}\times 100}$
$r=\sqrt{100}$

$=10$ cm