This is practical problem. I want to make a lampshade (actually many of them). It is made by rolling a piece of paper into a non-closed cone shape. The base is wider than the top.
Given: the length of a side, the top diameter, and the bottom diameter.
I need a formula that will take those three variables and output the X and Y dimensions of the piece of paper which will just inscribe the pattern. I can't even figure out whether this is a geometry, trig, or calculus problem.