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Homework Help: Vector Calculas: Simplifying expressions

  1. Jan 28, 2010 #1
    1. The problem statement, all variables and given/known data
    (a -b) [tex]\cdot[/tex] (b - c) [tex]\times[/tex] (c - a)

    2. Relevant equations

    3. The attempt at a solution

    Honestly I have no idea where to being. I believe this expression is a scalar triple product but I do not know how to use the properties to simplify this expression.

    Sorry, kind of screw up the latex symbols. Not sure how to use it probably.
  2. jcsd
  3. Jan 28, 2010 #2


    Staff: Mentor

    As you've written it, the expression doesn't make any sense. If you calculate (a - b) [itex]\cdot[/itex] (b - c), you get a scalar, which you can't cross with a vector. Do you mean
    (a - b) [itex]\cdot[/itex] ((b - c) X (c - a))?

    If so, here's a Wikipedia article that might be of help to you - http://en.wikipedia.org/wiki/Scalar_triple_product#Scalar_triple_product
  4. Jan 28, 2010 #3
    Perhaps but the book wrote it as (a - b) [itex]\cdot[/itex] (b - c) X (c - a). The book says the answers is 0 but I'm clueless as to where to begin. I'm guessing we have to simplify the cross product first.
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