1. The problem statement, all variables and given/known data The normal approach using the fundamental theorem of calculus seems inapplicable. I define a function B(R) based on a definite integral with one of the limits being R. One factor in the definite integral has R in it and that function vanishes to 0 at x = R. Using the fundamental theorem I run into the problem that the derivative of B(R) evaluates to 0. 2. Relevant equations K is just a constant greater than R. 3. The attempt at a solution Reversing the sign and the limits of integration is as far as I got. If I do a straight replacement of x with R, Cos-1(R/x) goes to Cos-1(1) which is zero... I'm trying to isolate G but this has me stumped.