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Homework Help: Magnitude of Vectors question!

  1. Jun 30, 2013 #1
    1. The problem statement, all variables and given/known data

    Is it always true that |A+B|=|A|+|B|?

    3. The attempt at a solution

    My quick answer to this question was no. But when i was asked why i really couldn't come up with much.

    any help is appreciated!
  2. jcsd
  3. Jun 30, 2013 #2
    Well, vector has direction. Thinking of the sum of vectors with different direction combinations ( same direction, different direction), then you will have your answer.
  4. Jun 30, 2013 #3


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    Science Advisor
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    Gold Member

    For an algebraic approach, consider that |X|2 = X.X (dot product). Square both sides of your equation and apply that.
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