A right triangle with sides 3 cm, 4 cm and 5 cm is rotated about the side of 3 cm to form a cone. The volume of the cone so formed is :

A. 12π cm³

B. 15π cm³

C. 16π cm³

D. 20π cm³

Answer: Option A

Solution(By Examveda Team)

Clearly, we have r = 3 cm and h = 4 cm
∴ Volume :
$$\eqalign{ & = \frac{1}{3}\pi {r^2}h \cr & = \left( {\frac{1}{3} \times \pi \times {3^2} \times 4} \right)\pi {r^3} \cr & = 12\pi {\text{ c}}{{\text{m}}^3} \cr} $$