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Math Help - Vectors

  1. #1
    Newbie usvn's Avatar
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    Vectors

    The line passes through points (0,.5,1) and (2,1,-3) find parametric equations and symmetric equations for the line


    I went ahead and subtracted (2,1,-3) from (0,.5,1) and ended up getting right answer, later to find out i subtract other way around to get right answer. Since its matters what which one subtracts from which one how do i determine which one to subtract from, the one with a higher z value? sorry the teacher never told me
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  2. #2
    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by usvn View Post
    The line passes through points (0,.5,1) and (2,1,-3) find parametric equations and symmetric equations for the line


    I went ahead and subtracted (2,1,-3) from (0,.5,1) and ended up getting right answer, later to find out i subtract other way around to get right answer. Since its matters what which one subtracts from which one how do i determine which one to subtract from, the one with a higher z value? sorry the teacher never told me
    as far as finding the equation of a line goes, it does not matter. the vectors you get will be parallel, just pointing in opposite directions, and so, either vector can be used as a direction vector for the line.

    in cases where the actual direction matters though, you always want the components of your vector to be given by the components of the terminal point minus the components of the initial point
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  3. #3
    Newbie usvn's Avatar
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    What if it doesnt state which one is the initial like this one
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    MHF Contributor Reckoner's Avatar
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    Quote Originally Posted by usvn View Post
    What if it doesnt state which one is the initial like this one
    Then it makes no difference which one you choose: Any direction vector will do. As Jhevon said, the order only matters in situations where the direction in which the line is traced out (i.e., its orientation) is important.
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