hi, i'm doing a maths assignment on "volume of solids of revolution" and stuck on one particular question. the question asks for the volume of the cross bounded by y=x, y=-x, y=x+2, y=-x+2 and the curve y=x^2-4. it is to be rotated around the y-axis. i really don't know how to do it, neither do my classmates. i had an idea of finding the area of the cross and rotating that but it wouldn't work out.

any ideas?

thanks in advanced.

here is a screenshot of the graph.