My problem is like this:

Evaluate the double integral of x(1+y^2)^(-1/2)dA where R is the region in the first quadrant enclosed by y=x^2, y=4 and x =0.

I try to solve as type I, that is I set the limit of integration with respect to y from x^2 to 4 and then limit of ontegration with respect to x from 0 to 2.

I use trigonometric subtitution which yields

y=tan(delta) and dy=sec^2(delta)d(delta)

then I dont know how to change the limit integration which respect to y into the limit integration which respect to delta.

Please help,

Thanks

P/s: this is my attached fomula:double integral.doc