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Homework Help: Vector in three dimensions

  1. May 16, 2007 #1
    1. The problem statement, all variables and given/known data

    Point A (2i +j 2k)
    Point B (3i +2j +5k)
    Point C (4i +5j -2k)

    the point d is such that abcd in that order is a parallelogram.

    Find position Vector D

    2. Relevant equations

    3. The attempt at a solution

    ok so i start of like this but im getting the wrong answer.
    http://img511.imageshack.us/img511/5946/vectorak5.jpg [Broken]


    but its wrong.
    Last edited by a moderator: May 2, 2017
  2. jcsd
  3. May 16, 2007 #2


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    It might be useful to make a drawing.
  4. May 16, 2007 #3
    Yes, but are those equations correct
    I've realized my error.
    culd you tell me the point of the unit vector.
    Last edited: May 16, 2007
  5. May 16, 2007 #4


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    You don't need to do anything involving norms or unit vectors here, so the square root stuff is way off base. It's really just a matter of vector addition, and subtraction.

    [tex]\vec{BA}=\vec{OD} - \vec {OC}[/tex]
    makes sense to me, the other equations don't really.
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