Hey there! Sign in to join this conversationNew here? Join for free
    • Thread Starter
    Offline

    13
    ReputationRep:
    I've been trying the paper below (Question 7). I've managed part a) but not part b).

    The diagram looks as if the curve is symmetrical about the initial line and from there I would have done a bit of geometry to find where S was and so on. But I didn't know how to prove the curve was symmetrical so I decided to look at the answer. The first line says OS = 8 and it's only worth 1 mark so it must be obvious. But I don't know why.

    Can anyone help please?

    http://filestore.aqa.org.uk/subjects...W-QP-JAN07.PDF

    http://filestore.aqa.org.uk/subjects...W-MS-JAN07.PDF
    • Study Helper
    Offline

    13
    Study Helper
    (Original post by maggiehodgson)
    I've been trying the paper below (Question 7). I've managed part a) but not part b).

    The diagram looks as if the curve is symmetrical about the initial line and from there I would have done a bit of geometry to find where S was and so on. But I didn't know how to prove the curve was symmetrical so I decided to look at the answer. The first line says OS = 8 and it's only worth 1 mark so it must be obvious. But I don't know why.

    Can anyone help please?

    http://filestore.aqa.org.uk/subjects...W-QP-JAN07.PDF

    http://filestore.aqa.org.uk/subjects...W-MS-JAN07.PDF
    What's the value of theta for OS? Look at the geometry.

    To show symmetry about the intial line you want to show r(\theta) = r(-\theta) treating r as a function of theta, which it is.
    • Study Helper
    Offline

    7
    ReputationRep:
    Study Helper
    (Original post by maggiehodgson)
    I've been trying the paper below (Question 7). I've managed part a) but not part b).

    The diagram looks as if the curve is symmetrical about the initial line and from there I would have done a bit of geometry to find where S was and so on. But I didn't know how to prove the curve was symmetrical so I decided to look at the answer. The first line says OS = 8 and it's only worth 1 mark so it must be obvious. But I don't know why.

    Can anyone help please?

    http://filestore.aqa.org.uk/subjects...W-QP-JAN07.PDF

    http://filestore.aqa.org.uk/subjects...W-MS-JAN07.PDF
    \cos\theta=\cos(-\theta) so curve must be symmetrical about the initial line
    • Thread Starter
    Offline

    13
    ReputationRep:
    (Original post by ghostwalker)
    What's the value of theta for OS? Look at the geometry.

    To show symmetry about the intial line you want to show r(\theta) = r(-\theta) treating r as a function of theta, which it is.
    Thank you. Learn such a lot on TSR.
    • Thread Starter
    Offline

    13
    ReputationRep:
    [QUOTE=brianeverit;52995273]\cos\theta=\cos(-\theta) so curve Thanks. Makes sense. Another trick to add to my notebook.
 
 
 
  • See more of what you like on The Student Room

    You can personalise what you see on TSR. Tell us a little about yourself to get started.

  • Poll
    Has a teacher ever helped you cheat?
    Useful resources

    Make your revision easier

    Maths

    Maths Forum posting guidelines

    Not sure where to post? Read the updated guidelines here

    Equations

    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
  • See more of what you like on The Student Room

    You can personalise what you see on TSR. Tell us a little about yourself to get started.

  • The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

    Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

    Write a reply...
    Reply
    Hide
    Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.