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) `1/3pir^3` (b)`2/3 pir^3` (c)`3pir^3` (d)`9pir^3`

Explanation

Given : Radius of base of cone = `3r`

height of cone = radius of base of cone =`3r`

Volume of cone=`(1/3)pir^2h`

Volume of cone = `1/3xxpixx(3r)^2xx3r` =`9pir^3`

Hence, option(d) is correct.