Hey! Sign in to get help with your study questionsNew here? Join for free to post

Torus Equation

Announcements Posted on
At uni? What do you think of the careers support? 12-02-2016
How proud of your uni are you? Take our survey for the chance to win a holiday! 09-02-2016
  1. Offline

    Let T be a circle with diameter AC=a, and let B be a point on T such that AB=b<a. Let T' be the semicircle with diameter AC in the plane perpendicular to that of T.

    Rotating T' around the perpendicular at A to the plane ABC generates a torus  \mathcal{T} of internal radius 0. Give the equation of  \mathcal{T} .

    I've started by drawing everything out. If the circle is in the x-y plane, with the point A as at the origin, then the perpendicular is the z axis and the semi circle T' is in the x-z plane. Rotating around the z axis I can't see how this produces a torus? At best I get an upper half of a torus?
  2. Offline

    (Original post by miml)
    At best I get an upper half of a torus?
    Yep, that's what I make it.

    Edit: There also seems to be redundant information there. Multipart question?
  3. Offline

    (Original post by ghostwalker)
    Yep, that's what I make it.

    Edit: There also seems to be redundant information there. Multipart question?
    Thanks, I think what they want is to extend the semi-circle to a circle in the x-z plane, rotate it, give the equation of the resulting torus and then for the following parts only consider the upper half.

    Archytas' solution to doubling the cube if you're interested.


Submit reply


Thanks for posting! You just need to create an account in order to submit the post
  1. this can't be left blank
    that username has been taken, please choose another Forgotten your password?
  2. this can't be left blank
    this email is already registered. Forgotten your password?
  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
    your full birthday is required
  1. By joining you agree to our Ts and Cs, privacy policy and site rules

  2. Slide to join now Processing…

Updated: October 23, 2012
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.

Today on TSR

Find out who won!

TSR community awards 2015

Would you be influenced by unis giving flexible offers (so you can miss by a grade)?
Useful resources

Make your revision easier


Maths Forum posting guidelines

Not sure where to post? Read here first


How to use LaTex

Writing equations the easy way

Student revising

Study habits of A* students

Top tips from students who have already aced their exams

Study Planner

Create your own Study Planner

Never miss a deadline again

Polling station sign

Thinking about a maths degree?

Chat with other maths applicants

Can you help? Study help unanswered threads

Groups associated with this forum:

View associated groups
Study resources
Quick reply
Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.