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Projections of vectors inquiry

  1. Feb 15, 2008 #1
    I was wondering if it is possible, in projections, to have a projected onto b equal to zero or undefined. In other words, when does a projected onto b equal zero and when is it undefined?
  2. jcsd
  3. Feb 15, 2008 #2


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    It is certainly possible, in fact common, to have the projection of vector a onto vector b equal to 0: as long as a is perpendicular to b.

    The "projection of a onto b" would be "undefined" if b itself has length 0.

    In general, the (scalar) projection of a on b is
    That's 0 if the dot product of a and b is 0 (a is perpendicular to b) and undefined if ||b||= 0.
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