Question

Find the altitude of a cylinder with with a radius of 9 and a surface area of approximately 791.68 units2.

Answer 1

In this question , it is given that we have a cylinder with with a radius of 9 and a surface area of approximately 791.68 units square.

The formula of surface area of cylinder is

`A= 2 \pi r^2 + 2 \pi r h`

Substituting the values of A and r, we will get

`791.68 = 2* \pi * 9^2  + 2 * \pi * 9*h \\ 791.68 = 162 \pi + 18 \pi h \\ 791.68 -162 \pi = 18 \pi h \\ h = (791.68 -162 \pi)/(18 \pi) \\ h =5 units`

So the height of the cylinder is 5 units .