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    A=(3,-4,2)
    B=(1,0,-2)
    L passes through A and has equation
    r=(3,-4,2)+x(-3,5,2)
    AB=(-2,4,-4)
    C lies on L such that angle ABC is a right angle. Find the coordinates of the point C.

    The answer is (-3,6,6) but I have no idea how to get to it :/

    Any help would be muchly appreciated
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    (Original post by hkooba)
    A=(3,-4,2)
    B=(1,0,-2)
    L passes through A and has equation
    r=(3,-4,2)+x(-3,5,2)
    AB=(-2,4,-4)
    C lies on L such that angle ABC is a right angle. Find the coordinates of the point C.

    The answer is (-3,6,6) but I have no idea how to get to it :/

    Any help would be muchly appreciated
    http://www.thestudentroom.co.uk/forumdisplay.php?f=38

    If you post in maths, you are more likely to get a response. I have asked for this to be moved there for you.
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    A general point on the line L has coordinates:



    Call this point C, with position vector

    The angle between vectors and is

    So first we have to find .









    Now, using the formula for the angle between two vectors:



    Given that the angle between the vectors is 90, cos90 = 0.







    So the point C on line L is where .



    Therefore,

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    (Original post by The_Big_E)
    A general point on the line L has coordinates:



    Call this point C, with position vector

    The angle between vectors and is

    So first we have to find .









    Now, using the formula for the angle between two vectors:



    Given that the angle between the vectors is 90, cos90 = 0.







    So the point C on line L is where .



    Therefore,

    Thank you, I get it now
 
 
 
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