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Math Help - vector

  1. #1
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    vector

    If u = 3i + 2j and v = -5i + 3j, find

    1.)the vector projection of v onto u.
    2.)the vector projection of u onto v.

    for #1, is it < -27/13 , -18/13 >
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  2. #2
    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by Mr_Green View Post
    If u = 3i + 2j and v = -5i + 3j, find

    1.)the vector projection of v onto u.
    2.)the vector projection of u onto v.

    for #1, is it < -27/13 , -18/13 >
    the vector projection of v onto u is given by: proj[u]v = (u.v/u.u)*u

    u.v = 3(-5) + 2(3) = -15 + 6 = -9
    u.u = 3(3) + (2)(2) = 9 + 4 = 13

    => proj[u]v = (-9/13)<3,2> = <-27/13, -18/13>

    you were correct!

    the second is the same procedure, you just switch the vectors around.


    see Vector Projection for more info
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