A-level maths help!

I'm not sure it's possible to be sure without context.

To me the most "natural" way of doing it is to know/derive that the volume of revolution is $\pi \int_{\pi/4}^{\pi/2} y^2 |\frac{dx}{dt}| \, dt$ which I think would be FM.

But you could also just work out y in terms of x and treat as a normal A-level volume of revolution question (which wouldn't require anything in the FM syllabus).

I'd suggest you try the second approach.

There is nothing to do with the volume of a revolution on the Edexcel specification for A-level maths and I have never been taught it.

Well in that case I don't see how it can be on your syllabus (also not sure why you asked the original question). It was definitely on my A-level syllabus but that was quite a while ago.

It's one of the main things that was moved out of C4 and into further maths with the new syllabus, PMT seem to have accidentally left quite a few of them in their new spec resources though unfortunately!