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  1. #1
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    line

    hey guys...i was just wondering if you could help me with these questions...
    like..ok vector equation of a plane that is paralell to 3x-9y+z-12=0 and goes thru the pt 3 -7 1.

    x,y,z= (3 -7 1) + s( ) + t( 3,1,0)

    how...do u find s?...
    and also if you had 3 pts...a, b, c...u would have to find ab..and ac...and cross product them...to find the normal rite?...then use a as ur pt...and how would u find the other directional vector for that?..

    thankssss <3
    Last edited by rabiatoor; October 13th 2008 at 08:15 PM.
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  2. #2
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    Quote Originally Posted by rabiatoor View Post
    hey guys...i was just wondering if you could help me with these questions...
    like..ok vector equation of a line that is paralell to 3x-9y+z-12=0 and goes thru the pt 3 -7 1.

    [snip]
    A vector in the direction of the line is <3, -9, 1>. A point on the line is (3, -7, 1).

    Therefore vector equation of line is r = (3, -7, 1) + t <3, -9, 1>
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  3. #3
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    umm but..arent u supposed to have 2 directional vectors?...
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  4. #4
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    Quote Originally Posted by rabiatoor View Post
    umm but..arent u supposed to have 2 directional vectors?...
    No. You're getting confused with the vector equation of a plane. Go back and read your notes.
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  5. #5
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    oh LOLZ
    thats what im looking for lolz
    i typed the wrong thing
    i was trying to find the vector equation of a plane please =]
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  6. #6
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    Quote Originally Posted by rabiatoor View Post
    oh LOLZ
    thats what im looking for lolz
    i typed the wrong thing
    i was trying to find the vector equation of a plane please =]
    Then I can't make much sense of your original post. Please post the question exactly as it's written.
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  7. #7
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    ok that is how it is written..
    i edited my original question
    thanks again =]
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  8. #8
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    Quote Originally Posted by rabiatoor View Post
    hey guys...i was just wondering if you could help me with these questions...
    like..ok vector equation of a plane that is paralell to 3x-9y+z-12=0 and goes thru the pt 3 -7 1.

    x,y,z= (3 -7 1) + s( ) + t( 3,1,0)

    how...do u find s?...
    and also if you had 3 pts...a, b, c...u would have to find ab..and ac...and cross product them...to find the normal rite?...then use a as ur pt...and how would u find the other directional vector for that?..

    thankssss <3
    A normal vector to your plane is <3, -9, 1> and the plane passes through the point (3, -7, 1). Try reading this: Finding equations of planes using normal vectors
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