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Homework Help: Vector geometry, some problems.

  1. Nov 12, 2009 #1
    I have two problems I need help with.
    1. The problem statement, all variables and given/known data
    ABCD is a parallellogram. E is the midpoint on BC. F is on AD so that |DF| = 8|AF|. G is the intersection between AE and BF.
    a) Express the vector AG as a linear combination of u = AB and v = AD.
    b) Show that the area of the triangle AFG always is the same fractional part of ABCD. Find that fractional part!


    2. Relevant equations

    3. The attempt at a solution
    I have no idae. Any help would be nice.
  2. jcsd
  3. Nov 12, 2009 #2


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    Science Advisor
    Homework Helper

    Hi Gramsci! :wink:

    Do it step by step …

    i] what is AE (in terms of u and v)?

    ii] what is AF?

    iii] so what is a general point on AE, and on BF? :smile:
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