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Homework Help: Vector perpendicular to two vectors

  1. Sep 11, 2011 #1
    1. The problem statement, all variables and given/known data
    A=(i+j-k) B=(2i-j+3k)
    Need to find vector perpenducilar to them

    2. Relevant equations



    3. The attempt at a solution
    I've solved by finding A*B and then divided it to (A*B), the result was W=2i/[itex]\sqrt{38}[/itex]-5j/[itex]\sqrt{38}[/itex]-3k/[itex]\sqrt{38}[/itex]. Is it correct?
     
    Last edited: Sep 11, 2011
  2. jcsd
  3. Sep 11, 2011 #2

    HallsofIvy

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    What do you mean by A*B? I know scalar product, dot product, and cross product of vectors but none of those use "*". And what is the difference between "A*B" and "(A*B)"? If you mean |A*B|, the length of the vector, I see no reason to divide. The problem did not ask for a unit vector.
     
  4. Sep 11, 2011 #3
    I mean AxB, and (AxB) means length of AxB. Do mean that my answer is not correct?
     
  5. Sep 11, 2011 #4

    HallsofIvy

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    No, I meant that I did not understand your answer. Yes, AxB is perpendicular to A and B and so satisfies the condition of the problem. And so AxB/|AxB| is a unit vector perpendicular to both A and B. But the problem did not ask for a unit vector.
     
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