I'm having some trouble with a question, I've got a lot of the difficult stuff down but I can't get the limits right and my answer is twice what it should be.

So I know that and that .Curve C:

The curve C is rotated through 360 degrees about the x-axis. Show that the curved surface area of the solid of revolution generated by:

Hence find this curved surface area.

So:

So I have the right integral but I can't show that the limits are 0 to .

I don't think it wants me to use symmetry as that would make it , I tried but I can't get the right answers.

Cheers