A doubt

If you got Int(dA) and A=xy, which are variables, how would that integration become in terms of x and y?

I have to say I agree with >>5.  What the hell is your notation?

Are you trying to integrate a function of x,y in 2D over some area of the xy plane?  What the hell is \A=((R^2)*y)/2 supposed to mean?  Are you integrating over a curved 2 surface, where the area element depends on the coordinates x,y?