Question

Mark the correct alternative of the following.
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?

Answer 1

Correct option is D. $$9\pi r^3$$
We know, volume of cone $$=\dfrac{1}{3}\pi r^2 h$$.

Here, it is given that, the base is $$3r$$ and that the vertical height is $$3r$$.....(Since height $$=$$ radius).

Substituting these values in the formula we get,

Volume of cone $$=\dfrac{1}{3}\pi \times (3r)^2\times (3r)$$

$$=\dfrac{1}{3}\pi\times 9r^2\times 3r$$

$$=9\pi r^3$$.

Therefore, option $$D$$ is correct.