Didn't I already do this one?
1) Make up your mind about the problem statement.
2) Axis of rotation is what?
3) Find the 12 intersections.
4) etc. What did I say before. I don't recall.
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.
thanks in advanced.
here is a screenshot of the graph.
Heres how I went about it:
Just consider one side. You can look at it as two branches. The top branch is still bounded by 3 lines. However, if we cut this area in half aloing the the intersection on the middle/outside, then each side is only two lines bouding the areas. If you follow the same pricinple for the bottomw branch, you will have 4 different areas rotated. The is one little bit of overlap, the triangle shape, but you can easily rotate that and subtract it from the total.