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Homework Help: Calculating the vector product

  1. Feb 9, 2009 #1
    i have a question i'm trying to find the cross product of the vector but don't know which formula to use.

    the first one is
    i(....) + j(....) + k (....)
    and the other one is the same as this one but has a negative sign
    i(....) - j(....) + k (....)

    what is the difference and which formula should i use?
  2. jcsd
  3. Feb 9, 2009 #2

    Tom Mattson

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    Staff Emeritus
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    Gold Member

    There is only one formula. You compute the following (formal) determinant.

    [tex]\hat{A}\times\hat{B} = \left|\begin{array}{ccc}\hat{i} & \hat{j} & \hat{k}\\a_1 & a_2 & a_3\\b_1 & b_2 & b_3\end{array}\right|[/tex]

    where [itex]\hat{A}=\left<a_1,a_2,a_3\right>[/itex] and [itex]\hat{B}=\left<b_1,b_2,b_3\right>[/itex].
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