A practice in double integral

Evaluate (1) ∫∫_D 1/√[(x-y)²+2(x+y)+1] dA (2)∫∫_D 1/√[(x+y)²+2(x-y)+1] dA,
where D={ (x,y) | 0 < x < 2, 0 < y < x }.

試求(1) ∫∫_D 1/√[(x-y)²+2(x+y)+1] dA (2)∫∫_D 1/√[(x+y)²+2(x-y)+1] dA,
其中D={ (x,y) | 0 < x < 2, 0 < y < x }.