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

    2
    ReputationRep:
    I'm struggling to follow the proof for the first question of the problems i.e. USAMO 2001/02. I'm not sure how they derived Q' + P = A + D2 for the y-coordinate. I understand how they derived the expression but not sure as to why it applys only to the y-coordinate and the bit about the Qz too, why is z-coordinate the ratio of z to y of P. Finally I don't get how Q is diametrically opposite to D1. Many thnx for any help.
    • Community Assistant
    • Welcome Squad
    Offline

    20
    ReputationRep:
    Community Assistant
    Welcome Squad
    (Original post by 11234)
    I'm struggling to follow the proof for the first question of the problems i.e. USAMO 2001/02. I'm not sure how they derived Q' + P = A + D2 for the y-coordinate. I understand how they derived the expression but not sure as to why it applys only to the y-coordinate and the bit about the Qz too, why is z-coordinate the ratio of z to y of P. Finally I don't get how Q is diametrically opposite to D1. Many thnx for any help.
    Link/post the question.
    • Thread Starter
    Offline

    2
    ReputationRep:
    (Original post by RDKGames)
    Link/post the question.
    sorry
    http://www.mit.edu/~evanchen/handout.../bary-full.pdf
    • Thread Starter
    Offline

    2
    ReputationRep:
    (Original post by RDKGames)
    Link/post the question.
    do you have any tips for bmo2 especially barycentric and projective geometry
    Offline

    15
    ReputationRep:
    (Original post by 11234)
    I'm struggling to follow the proof for the first question of the problems i.e. USAMO 2001/02. I'm not sure how they derived Q' + P = A + D2 for the y-coordinate. I understand how they derived the expression but not sure as to why it applys only to the y-coordinate and the bit about the Qz too, why is z-coordinate the ratio of z to y of P. Finally I don't get how Q is diametrically opposite to D1. Many thnx for any help.
    The midpoint of Q'P is the midpoint of AD_2 as AQ' is of the same length as PD_2
    • Thread Starter
    Offline

    2
    ReputationRep:
    (Original post by RichE)
    The midpoint of Q'P is the midpoint of AD_2 as AQ' is of the same length as PD_2
    ok but why equate y coordinates
    Offline

    15
    ReputationRep:
    (Original post by 11234)
    ok but why equate y coordinates
    Don't think it matters which co-ordinate the answer starts with. Each one is found in turn.
 
 
 
  • 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
    Would you like to hibernate through the winter months?
    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

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