1. The problem statement, all variables and given/known data I have been hung up on this integral: (μ /4∏ε) ∫ dz/(√s^2 + z^2) 2. Relevant equations 3. The attempt at a solution i have tried a couple of different u-substitutions, and none are getting me anywhere. I do not that partial fractions, or by parts would help either. I know what the integral equals (integral table), but i should like to know how to calculate it.