the volume of a cylinder is

is the radius, and is the height.

solve that for , and then plug in and

we have the difference of two squares here:2. Expand and simplify the expression π(R+r)(R-r) to explain why it represents the area of a ring. Draw a diagram of the ring and identify R and r.

and can somebody give me a website to learn how to solve these types of problems it would be much appreciated.

now what can you say? did you draw the diagram? the inner radius is r and the outer radius is R