Question

A cylinder and a cone have the same volume. The cylinder has radius x and height y. The cone has radius 1/3x. Find the height of the cone in terms of y.

Answer 1

The height of the cone h = 27(x^4)y

Explanation:

Firstly, we calculate the volume of the cylinder.

Mathematically, the volume of the cylinder is pi * r^2 * h

using the radius x and height y

The volume V of the cylinder is ;

V = pi * x^2 * y

Now we know they have the same volume V, the formula for the volume of a cone is ;

1/3 * pi * r^2 * h

Substituting the values of r to be 1/3x and the height which is not given here left as h, we have the volume of the cone to be;

V = 1/3 * pi * (1/3x)^2 * h = pi * x^2 * y

The pi gives way as it cancels out on both sides and we have the following;

h/27x^2 = x^2y

Mathematically h = x^2 * y * 27x^2

h = 27(x^4)y

p.s: I personally feel the radius of the cone was to be given as x/3 and not 1/3x . It is in that way we can have the height of the cone purely in y terms and no x