You are Here: Home >< Maths

# Volumes of Revolution

Announcements Posted on
Why bother with a post grad course - waste of time? 17-10-2016
1. Question:Find the volume generated when the region bounded by the curve y=x^2, the x-axis and the line x=2, is rotated through 180 degrees about the line x=3.

I've found that the line x=2 and the curve cross at (2,4) so my limits are 4 and 0. How would I form an equation to find the volume using pi ∫ x^2 dy to find the volume? Can x=a even be written as a function of y?

Posted from TSR Mobile
2. (Original post by Mr Pussyfoot)
Question:Find the volume generated when the region bounded by the curve y=x^2, the x-axis and the line x=2, is rotated through 180 degrees about the line x=3.

I've found that the line x=2 and the curve cross at (2,4) so my limits are 4 and 0. How would I form an equation to find the volume using pi ∫ x^2 dy to find the volume? Can x=a even be written as a function of y?
Since you're rotating about x=3, if you translate the curve then you're rotating about the y-axis. So you need to find things as a function of x, not as a function of y.

## Register

Thanks for posting! You just need to create an account in order to submit the post
1. this can't be left blank
2. this can't be left blank
3. this can't be left blank

6 characters or longer with both numbers and letters is safer

4. this can't be left empty
1. Oops, you need to agree to our Ts&Cs to register

Updated: July 23, 2016
TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Today on TSR

### A level maths

Which modules should I take?

Poll
Useful resources

### Maths Forum posting guidelines

Not sure where to post? Read here first

### How to use LaTex

Writing equations the easy way

### Study habits of A* students

Top tips from students who have already aced their exams