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Homework Help: Scalar multiplication of two equal vectors

  1. Nov 18, 2008 #1
    i have vector "a"

    why a*a=1??

    it make no sense

    the formula says |a|*|a|*cos0=a^2 (not 1)
     
  2. jcsd
  3. Nov 18, 2008 #2

    tiny-tim

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    Hi transgalactic! :smile:
    But cos0 = 1,

    so that means |a|*|a| = a^2, which is correct. :smile:

    Where does your a*a=1 come from? :confused:
     
  4. Nov 18, 2008 #3
    from my professor in physics :(
     
  5. Nov 18, 2008 #4

    tiny-tim

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    Well, what was the context, then?

    What else was he/she talking about at the time?

    Unit vectors? Basis vectors? General vectors? Hilbert spaces?
     
  6. Nov 18, 2008 #5
    he just stated that if we multiply scalarly a vector(in general) by itself
    we will get 1
     
  7. Nov 18, 2008 #6

    tiny-tim

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    hmm … that's obviously rubbish …

    i suppose he must have been thinking of applying that to some specific equation that he didn't actaully mention. :confused:
     
  8. Nov 18, 2008 #7
    ill try to confront him with this problem
     
  9. Nov 18, 2008 #8

    HallsofIvy

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    Are you sure he didn't say a unit vector?
     
  10. Nov 18, 2008 #9
    unit vector represents a single unit with the direction of a certain axes
    i think you are correct
    why their multiplication equals 1?

    nobody said their length is 1
    only that its the smallest unit of length with a direction

    ??
     
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