1. The problem statement, all variables and given/known data Evaluate the double integral over R of cos[(y-x)/(y+x)] dA where R is the trapezoidal region with vertices (1,0) (2,0) (0,1) and (0,2). 3. The attempt at a solution First I set u=y-x, v=y+x. I have 4 sides in the xy-plane that need to be transformed into the uv-plane. Side 1 is y=-x+2, Side 2 is y=-x+1, and then Side 3 & 4 are 0<x<2 (where the less than sign signifies less than or equal to). I solved for v, and got v=1, v=2, so I have those limits. But I can't figure out how to find the limits for u.