The problem is as follows. Calculate the double integral of cos ((x-y)/(x+y)) dA over R, where R is the triangle bounded by the points (0,0), (2,2), and (2 + pi, 2 - pi). I understand that you have to set U = x-y and V = x+y. However, I am having a hard time finding the bounds on the integral because the slope of the lines isn't 1. I can't simply add x to the other side of each equation because of the 2+pi and 2-pi. Any help would be appreciated. Thanks!