Graveyard

A uniform annulus with mass $M$ has an inner radius of $R_1$ and an outer radius of $R_2.$ Compute the moment of inertia of the annulus about its axis of symmetry.

When you get your answer, check the following two cases: $$R_1 = R_2 = R$$ $$R_1 = 0, R_2 = R$$ What does the annulus look like in these cases? Does your answer agree with what you already know about these special cases?