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Homework Help: What is the angle between these two vectors?

  1. Oct 27, 2011 #1
    Vectors A and B have scalar product -4.00 and their vector product has magnitude 9.00.

    Here's what I did:

    ABcos=-4
    ABsin=9

    sin/cos=-2.25

    tan=-2.25

    angle=-66?

    I entered this and it says it's incorrect. What did I do wrong?
     
  2. jcsd
  3. Oct 27, 2011 #2
    Pay attention that the angle between two vectors won't be negative ...

    There should be an angle that its cos is - and its sin is +

    angle: 180 - 66 = 114 degree
     
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