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

    13
    ReputationRep:
    Hey can anyone help me answer this question, 5 marks
    Name:  20170202_195700.jpg
Views: 191
Size:  421.1 KB
    • Thread Starter
    Offline

    13
    ReputationRep:
    Infact don't worry I know how to solve it.

    The vector AR can be found in two different ways in which they are both equal in each other, therefore I can re-arrange for r

    Spoiler:
    Show

    Correct me if I'm wrong tho
    Offline

    11
    ReputationRep:
    Since R divides AB into the ration m:n, \frac{AR}{RB} = \frac{m}{n}. Then rearrange to find r
    Offline

    11
    ReputationRep:
    (Original post by CraigBackner)
    Infact don't worry I know how to solve it.

    The vector AR can be found in two different ways in which they are both equal in each other, therefore I can re-arrange for r

    Spoiler:
    Show


    Correct me if I'm wrong tho

    I don't think that will work. since the vectors when you find AR in the other way will cancel to leave your original AR
    • Thread Starter
    Offline

    13
    ReputationRep:
    (Original post by h3rmit)
    Since R divides AB into the ration m:n, \frac{AB}{RB} = \frac{m}{n}. Then rearrange to find r
    should't the equation be \frac{AR}{RB} = \frac{m}{n}?
    Offline

    11
    ReputationRep:
    (Original post by CraigBackner)
    should't the equation be \frac{AR}{RB} = \frac{m}{n}?
    Yes, and that's what I typed first time correctly with 100% definitely no mistakes.
    Offline

    17
    ReputationRep:
    h3rmit is correct although  \displaystyle \frac{AB}{RB} = \frac{m+n}{n}

    edit: im so confused with edits
    • Thread Starter
    Offline

    13
    ReputationRep:
    (Original post by h3rmit)
    I don't think that will work. since the vectors when you find AR in the other way will cancel to leave your original AR
    The vector AR is r-a and the second vector is  \frac{m}{m+n}\left(AB\right) which equals \frac{mb-ma}{m+n}


    when these two are equal and you rearange for r you get \frac{mb+na}{m+n}

    which is the given expression
    Offline

    11
    ReputationRep:
    (Original post by CraigBackner)
    The vector AR is r-a and the second vector is (m)/(m+n)(AB) which equals (mb-ma)/(m+n)

    when these two are equal and you rearange for r you get (bm+an)/(m+n)

    which is the given expression
    Ah, I thought you meant using the triangle and a, r, and b only
    • Thread Starter
    Offline

    13
    ReputationRep:
    It's not even a proof question but a show me
 
 
 
  • 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
    What newspaper do you read/prefer?
    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.