Find the volume of the right circular cone with

Question. Find the volume of the right circular cone with

(i) radius 6 cm, height 7 cm

(ii) radius 3.5 cm, height 12 cm

$\left[\right.$ Assume $\left.\pi=\frac{22}{7}\right]$

Solution:

(i) Radius (r) of cone = 6 cm

Height $(h)$ of cone $=7 \mathrm{~cm}$

$=\left[\frac{1}{3} \times \frac{22}{7} \times(6)^{2} \times 7\right] \mathrm{cm}^{3}$

$=(12 \times 22) \mathrm{cm}^{3}$

$=264 \mathrm{~cm}^{3}$

Therefore, the volume of the cone is $264 \mathrm{~cm}^{3}$.

(ii) Radius $(r)$ of cone $=3.5 \mathrm{~cm}$

Height $(h)$ of cone $=12 \mathrm{~cm}$

Volume of cone $=\frac{1}{3} \pi r^{2} h$

$=\left[\frac{1}{3} \times \frac{22}{7} \times(3.5)^{2} \times 12\right] \mathrm{cm}^{3}$b

$=\left(\frac{1}{3} \times 22 \times \frac{1}{2} \times 3.5 \times 12\right) \mathrm{cm}^{3}$

$=154 \mathrm{~cm}^{3}$

Therefore, the volume of the cone is $154 \mathrm{~cm}^{3}$.b