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Vector help

  1. Sep 4, 2005 #1
    Hello, can anyone guide me with this problem?

    Find nonzero vectors a ,b , and c such that a x b = a x c but b does not equal c

    I would appreciate any help. Thanks
  2. jcsd
  3. Sep 4, 2005 #2
    The cross product is zero for perpendicular vectors so the cartesian unit vectors would satisfy that as i x j = i x k =0.
  4. Sep 4, 2005 #3
    That's all wrong. The dot product is zero for perpendicular vectors.
    The cross product is i x j = k.
  5. Sep 4, 2005 #4


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    Gold Member

    Yeah, the cross product is zero for parallel vectors. So (1,1,1) x (2,2,2)= (1,1,1) x (3,3,3) = (0,0,0) is a solution.
  6. Sep 4, 2005 #5
    Oh hell. I got my products mixed. Scratch that advice and sorry if I caused any problems.
  7. Sep 4, 2005 #6
    We just need that c=b+ka so that c-b is parallel to a
    (a,b,b+ka) satisfies the prop(k is a scalar not equal to zero)
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