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Math Help - Find vector C!

  1. #1
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    Find vector C!

    Given A= [1,1,1] and B=[2,-1,0] Find vector C which is Coplanar With A and B and perpendicular to A My solution:1. The triple product for ll those three vectors should equal 0 (i.e. A.(BXC)= 0)2. A.C=0 (i.e using Dot product)So, I've 2 equations and i can't get C can anybody help, Urgently please?
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  2. #2
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    Re: Find vector C!

    Quote Originally Posted by ahmedzoro10 View Post
    Given A= [1,1,1] and B=[2,-1,0] Find vector C which is Coplanar With A and B and perpendicular to A
    What about (A\cdot B)A-(A\cdot A)B~?
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  3. #3
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    Re: Find vector C!

    more explain,please
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    Re: Find vector C!

    Quote Originally Posted by ahmedzoro10 View Post
    more explain,please
    No. You have to do somethings for yourself.
    Have you done those operations.
    Is the result coplanar with A & B?
    Is it perpendicular to A?
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  5. #5
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    Re: Find vector C!

    I've already 2 equations which consist of x,y and Z for C
    First, A, B and C are already coplanar so I got the first equation which is x+2y-3z=0
    then, A and C are coplanar so i got the sec. equation which is x+y+z=0
    and I can't go on
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  6. #6
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    Re: Find vector C!

    A and C are orthogonal*
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  7. #7
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    Re: Find vector C!

    yes there're
    how did you get this formula?!
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  8. #8
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    Re: Find vector C!

    yes they're!!
    how did you get this formula?!
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  9. #9
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    Re: Find vector C!

    Quote Originally Posted by ahmedzoro10 View Post
    yes they're!!
    how did you get this formula?!
    This well known triple vector product:
    A\times(B\times C)=(A\cdot C)B-(A\cdot B)C.
    That is a vector which is coplanar with B~\&~C and is perpendicular to A.
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  10. #10
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    Re: Find vector C!

    yes i got it thanks
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