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Homework Help: Finding vector magnitude

  1. Feb 12, 2008 #1
    Find a vector whose magnitude is 4 and whose x component is twice its y component.

    I know that to calculate magnitude it is r= sqrt (x1 + x2)2 + (y1 + y2)2.

    I also know that k(vector)= 4

    I just am confused by the components (so x=2y ....)
  2. jcsd
  3. Feb 12, 2008 #2


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    Homework Helper

    Let a=xi+yj

    now |a|=4
    so that [itex]4=\sqrt{x^2+y^2}[/itex]...(*)

    You are told x=2y...can you use this fact and (*) to help you find x and y now?
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