Question 1065224
A drawing would help.


r, radius of the cylinder
h, height of the cylinder


Similar triangles can be identified from a drawing.
{{{(R-r)/h=R/H}}}


{{{h=(R-r)(H/R)}}}


V, volume for the cylinder,
{{{V=h*pi*r^2}}}

{{{V=(R-r)(H/R)*pi*r^2}}}