Thread: volume of solids of revolution

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. 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.

1) Decide whether or not this belongs in PREcalculus.
2) Find ALL the intersections. ALL of them. I count at least 12 that should be labled.
3) Find the rest of the problem statement. About what are we revolving?
4) Consider symmetries as possibilities for simplifying your life.
5) Your plan MAY be effective. Do you get to use the Theorem of Pappas?
6) You tell me...

Duplicate question, dealt with here: http://www.mathhelpforum.com/math-he...ion-99217.html.