I have this question which is rather interesting and quite hard IMO.

I have to find the volumes of revolution generated by the regions A and B when they areeachrotated about: thexaxisandtheyaxis

If the equation was http://thestudentroom.co.uk/latexren...e9f3f6cc14.png from a to b,then it means I need to find the volume of revolution for:

- x = a to b, rotated around the x axis, which would be: http://thestudentroom.co.uk/latexren...6143c3210b.png http://thestudentroom.co.uk/latexren...5e42a40994.png http://thestudentroom.co.uk/latexren...31db07d46e.png
- y = a to b, roated around the y axis, which would be: http://thestudentroom.co.uk/latexren...08e88fd550.png http://thestudentroom.co.uk/latexren...5e42a40994.png http://thestudentroom.co.uk/latexren...4cf0f594b8.png

are those right?

I also have to find this though and this is what I need help with:

- x = a to b, rotated around the y axis
- y = a to b, roated around the x axis

I dont know what to do for this though