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Math Help - vector

  1. #1
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    vector

    Let a = (8, 3, 5) and b = (8, -10, -5) be vectors. Find the scalar, vector, and orthogonal projections of b onto a .

    I was able to easily find the scalar and vector projection, but I need help on orthogonal projection. All I know is that the dot production must equal 0.

    Scalar projection = 9/sqrt(98)

    Vector projection = ( 36/49 , 27/98 , 45/98 )

    -Thanks
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  2. #2
    o_O
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    The orthogonal projection of b onto a is given by: \text{proj}_{\bold{a}} \bold{b} = \frac{\bold{b} \cdot \bold{a}}{|| \bold{a} ||^2} \bold{a}

    Just plug n' chug.
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  3. #3
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    No..

    that gives me vector projection.
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  4. #4
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    \frac {36}{42}v_1 + \frac {27}{98}v_2 + \frac{45}{98}v_3 = 0

    How would I find these three points.
    Because  {u}\cdot{v} = 0 means that they are perpendicular to each other
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