Question:
The volume of a right circular cone of height 12 cm and base radius 6 cm, is
(a) $(12 \pi) \mathrm{cm}^{3}$
(b) $(36 \pi) \mathrm{cm}^{3}$
(c) $(72 \pi) \mathrm{cm}^{3}$
(d) $(144 \pi) \mathrm{cm}^{3}$
Solution:
(d) $(144 \pi) \mathrm{cm}^{3}$
Volume of the cone $=\frac{1}{3} \pi r^{2} h$
$=\frac{1}{3} \pi \times 6^{2} \times 12$
$=\pi \times 36 \times 4$
$=144 \pi \mathrm{cm}^{3}$