Mass of Surface: Find Double Integral over S

[chancellorpho]

Homework Statement

If the mass per unit area of a surface is given by rho = x*y, find the mass
double integral over S of x*y dS if S is the part of the cylinder x^2 + z^2 = 9 which is in the first octant and contained within the cylinder x^2 + y^2 = 4.

Homework Equations

Above.

The Attempt at a Solution

I can visualize what the shape looks like, but I'm not sure how to define the bounds of integration based on the shape described.

 

[chancellorpho]

does anyone have any ideas? help would be greatly appreciated.

 

[Billy Bob]

Make sure you're visualizing the shape from a useful viewpoint. I suggest looking "from above." In other words, draw the xy-plane as usual on your paper, position your eye directly above the origin, and imagine the z-axis pointing straight out at your eye. Shade the region in the xy-plane that is covered by the surface.