If R is the triangle bounded by x+y = 1, x = 0, y =0, evaluate the double integral over R of cos((x+y)/(x-y)) dx dy by changing variables. Leave your answer in terms of sin(1).

We have to calculate following double integral.
Here R is triangular region bounded by x+y=1,x=0,y=0
Now by change of variable method we will put u=x+y and v= x-y
so x=(u+v)/2 and y=(u-v)/2
Now point(x,y) varies in triangular region R, So let’s suppose point(u,v) varies in region P
Now x+y=1, y=0,x=0
when...