1. The problem statement, all variables and given/known data 2. Relevant equations 3. The attempt at a solution I know some of you may have given up on me understanding moment of inertia/second moment of area, but here is another problem. I am using the this table to get the equations for the polar moment of area of a hemicircle around the x-axis, then I am applying the parallel axis theorem to find the polar moment of inertia. The answer in the back of the book doesn't even have the term a in it, which is what I don't get.