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Math Help - Vector Question Help!!

  1. #1
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    Vector Question Help!!

    The line L has a vector equation of r=2i-j+4k + s(i+j-k)

    the point P lies on line L and the point Q has position vector of 2i-k

    Q: Given that line PQ is perpendicular to L find the position vector of P?

    can someone help me with this question please thanks in advacne
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  2. #2
    Member Greengoblin's Avatar
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    So L passes through (2, -1, 4), and\ (1+2, 1-1, -1+4) = (3, 0, 3)

    Now what you are looking for is the shortest path from the line to the point, which happens to be perpendicular...meaning the dot products of the two lines = 0. Does that help you?
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  3. #3
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    soo what ur saying is tht 3,0,3 is a point on the line??sorry i still dont quite get it im really bad with vectors cud u explain more details plz
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