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Homework Help: Vector Problem

  1. Jan 10, 2010 #1
    1. The problem statement, all variables and given/known data
    You are given vectors vec A= 4.6i - 6.6j and vec B= - 3.0i + 7.2j. A third vector vec C lies in the xy-plane. Vector vec C is perpendicular to vector vec A and the scalar product of vec C with vec B is 18.0. (the i and j are hat values, they have a ^ over them)

    2. Relevant equations
    C * B = 18
    C * B = |C|*|B|cos(x)
    A * C = 0, because they are parallel

    3. The attempt at a solution
    I used the two equations
    (Cx)(Bx)+(Cy)(By) = 18
    (Ax)(Cx)+(Ay)(Cy) = 0

    but could not reach a solution. I would greatly appreciate some guidance
  2. jcsd
  3. Jan 10, 2010 #2
    You are given Bx, By, Ax, Ay, so you simply have 2 equations with 2 unknowns which you can solve for by a number of ways.
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