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Vector divide with negative ratio?

  1. Oct 6, 2015 #1
    1. The problem statement, all variables and given/known data

    Find the position vector of point P if P divides AB in the ratio 5:-2 given A (-1,6,4) and B (4,1,-1)

    3. The attempt at a solution

    The only trouble I have is to understand the question...

    Does it mean something like

    A------------------>B<----------------------P
    3 2

    Or

    A----------------->P<-----------------------B
    5 2


    Please help
     
  2. jcsd
  3. Oct 6, 2015 #2

    andrewkirk

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    What strange terminology! I've not seen anybody use ratios with vectors that way before.
    I can only guess that when they say 'P divides AB in the ratio r:s' they mean
    $$\frac{\vec{AP}}{r}=\frac{\vec{PB}}{s}$$

    Which of your two options does that favour?
     
  4. Oct 7, 2015 #3
    Hmm... I just don't understand what the negative sign means...
    Is it really strange to use ratio with vectors? It's on the subchapter "Ratio Theorem" in Vector chapter.
     
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