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Product of 2 vectors help

  1. May 13, 2008 #1
    1. The problem statement, all variables and given/known data

    r.k where r=xi+yj+zk



    3. The attempt at a solution

    is the answer to this just z or is it x+y
     
  2. jcsd
  3. May 13, 2008 #2

    cristo

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    Well, why do you think it is either of the answers you quote?

    What is the definition of the dot product of two vectors?
     
  4. May 13, 2008 #3
    Dot product of 2 vectors a.b is a1b1+a2b2+a3c3?
     
  5. May 13, 2008 #4
    i think k.k = 0
     
  6. May 13, 2008 #5

    cristo

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    Ok, good. So, presumably, this definition is for two vectors a=(a1,a2,a3) and b=(b1,b2,b3). Can you write your two vectors in this form?

    Hold on.. this doesn't agree with what you stated above. Have another think...
     
  7. May 13, 2008 #6
    xi+yj+zk.k so this is x0+y0+z1 = z?
     
  8. May 13, 2008 #7

    cristo

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    Yup, that's correct.
     
  9. May 13, 2008 #8
    thanks a mill
     
  10. May 13, 2008 #9

    cristo

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    No problem!
     
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