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Homework Help: Magnitude of the Sum of Vectors

  1. Sep 24, 2008 #1
    I'm studying for an intro Physics exam and encountered this problem on my study guide:

    "A vector of magnitude 20 is added to a vector of magnitude 25.The magnitude of this sum can be:
    A) 50
    B) 12
    C) 3
    D) zero
    E) none of these are possible. "

    The professor told us the answer was B), but I don't understand why.

    I understand that the maximum you can get with these 2 vectors is the sum (20+25=45) and that the minimum you can get is the difference (25-20=5). I don't get where the 12 is coming from though. If anyone could point me in the right direction, that would be great. Thanks!
  2. jcsd
  3. Sep 24, 2008 #2


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    Homework Helper

    The vectors can be at an angle with respect to each other. Figure out what the angle could be based on the magnitude of the resultant vector and you will see why it's the right answer.
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