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Homework Help: Cross Products Help

  1. Feb 22, 2014 #1
    1. The problem statement, all variables and given/known data

    Given two vectors A⃗ = 4i + 7j and B⃗ = 5i − 2j , find the vector product A⃗ × B⃗ (expressed in unit vectors).
    Express your answer in terms of the unit vectors i, j, and k.

    2. Relevant equations

    3. The attempt at a solution

    I know how to cross and multiply them but they don't give the z component so I assumed it was zero

    This is what I got

    0i + 0j - 43k

    Why is that wrong ?, I'm doing this online assignment and it keeps telling me, "The correct answer does not depend on i,j and k"
  2. jcsd
  3. Feb 22, 2014 #2
    You did it right. They probably just want -43k.

  4. Feb 22, 2014 #3
    Yeah, I guess they just wanted -43k with the hat on top. Stupid system, now I lost 3% for each "wrong" attempt :mad:

    Thanks for your reply
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