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Homework Help: Finding the angle of 3-dimensional vectors.

  1. Sep 23, 2007 #1
    How would the angle between two vectors be found, if, for each vector, three components (i, j, k) were given?

    Ex. Given that vector A = 2.0 i + 4.0 j - 7.0 k and vector B = 5.0 i - 3.0 j + 1.0 k, what is the angle between A and B?
  2. jcsd
  3. Sep 23, 2007 #2
    Use the definition of the scalar (dot) product.
    Last edited: Sep 23, 2007
  4. Sep 23, 2007 #3

    We can find it by dot product.We know that for two vectors A and B

    [tex]\vec{A} \cdot \vec{B} = AB\cos\theta[/tex]

    Hence find A dot B and divide it by AB. And take its arccosine and you will get your angle.
  5. Sep 23, 2007 #4

    All right. I'm pulling out some of my old Pre-Cal stuff, when I learned that. :DDD

    Thank you.
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