help

We can use the Pythagorean Theorem to find the height of the cylinder 

We have

height  = √ [ 5^2 - 2^2 ]  = √[25 - 4]   =  √21  units

Here is a cross-section of this : 

A right circular cylinder with radius 2 is inscribed in a hemisphere with radius 5 so that its bases are parallel to the base of the hemisphere. What is the height of this cylinder?

https://free-picload.com/images/2019/07/30/214.jpg

this is the picture Omi 67 putt.