Question

If the radius of the base of a right circular cone is 3r and its height is equal to the radius of the base, then its volume is

(a) $\frac{1}{3}{\mathrm{\pi r}}^3$

(b) $\frac{2}{3}{\mathrm{\pi r}}^3$

(c) $3{\mathrm{\pi r}}^3$

(d) 9${\mathrm{\pi r}}^3$

Answer 1

The formula of the volume of a cone with base radius ‘r’ and vertical height ‘h’ is given as

Volume of cone =

Here it is given that the base radius is ’3r’ and that the vertical height is ‘3r’

Substituting these values in the above equation we get

Volume of cone =

=

Hence the correct answer is option (d).