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Homework Help: Direction Vector

  1. Apr 30, 2009 #1
    1. The problem statement, all variables and given/known data

    I have two x,y,z coordinates - a & b. I know the distance between the coordinates. I need to get a 3D vector which represent the direction between vector a and vector b.

    2. Relevant equations

    I am unsure as to whether the I should simply substract each respective coordinate value from one to the other i.e. (x1-x2,y1-y2,z1-z2)

    3. The attempt at a solution

    I tried to apply the forumula above to a trivial case e.g.

    A = (1,1,1); B = (2,2,2); C=(2-1,2-1,2-1,)=(1,1,1)

    I am not sure if this is right.
  2. jcsd
  3. Apr 30, 2009 #2


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    That's right.
  4. Apr 30, 2009 #3
  5. May 1, 2009 #4
    On a side note - how can i calculate the second vector from the first vector and the direction vector? Would l just add the direction vect to the first vector?
  6. May 1, 2009 #5


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    obviously, if d = b - a, then b = a + d!:smile:
  7. May 2, 2009 #6
    Thanks again!
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