# The height of a cone is 15 cm.

Question.

The height of a cone is $15 \mathrm{~cm}$. If its volume is $1570 \mathrm{~cm}^{3}$, find the diameter of its base. [Use $\left.\pi=3.14\right]$

Solution:

Height (h) of cone = 15 cm

Let the radius of the cone be r.

Volume of cone $=1570 \mathrm{~cm}^{3}$

$\frac{1}{3} \pi r^{2} h=1570 \mathrm{~cm}^{3}$

$\Rightarrow\left(\frac{1}{3} \times 3.14 \times r^{2} \times 15\right) \mathrm{cm}=1570 \mathrm{~cm}^{3}$

$\Rightarrow r^{2}=100 \mathrm{~cm}^{2}$

⇒ r = 10 cm

Therefore, the diameter of the base of cone is 10×2=20 cm