1. The problem statement, all variables and given/known data I have some questions similar to this one. I have to just provide reasoning as to why this can or cannot be evaluated using greens theorem. given f = x/sqrt(x^2+y^2) dx + y/sqrt(x^2+y^2) dy, and the curve c is the unit circle around the origin. Why can/cannot the integral of f around c be evaluated using greens theorem? 2. Relevant equations 3. The attempt at a solution So I said that because taking P as the first term and Q as the second term of f, they both don't have continuous first order partials on c (which is a condition for greens theorem) because there are restrictions on what x and y can be (ie x^2 + y^2 > 0). I'm not sure if that is right though if someone can clarify.