an some1 please help me with the following 2 question, i have attemped both but seem to come out with the correct answer:

1. ∫dx ∫(x-y)dy the 1st integral sign has the limits a and 0. the 2nd sign has the limits y1 and 0. where y1 = (a^2 -x^2)^0.5

for this ques the answer should be 0.

2. by changing the order of integration evaluate:

∫dx∫y^-1 sinycos(x/y)dy for the 1st integral sign, limits are 1 and 0. the 2nd sign has limits 1 and x.

answer: sin1(1-cos1)