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Coplanar vectors

  1. Sep 27, 2012 #1
    I have two vectors:

    r1v=r1x*i + r1y*j + r1z*k
    r2v=r2x*i + r2y*j + r2z*k


    r1=Math.sqrt(r1x^2 + r1y^2 + r1z^2)
    r2=Math.sqrt(r2x^2 + r2y^2 + r2z^2)

    How do I find out if they are coplanar or not?

    I know if they are perpendicular:

    r1v cross r2v = 0
  2. jcsd
  3. Sep 27, 2012 #2


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    Gold Member

    You can use the next criterion:

    Though I am not sure how you can find from your vectors the 4 points.

    But obviously if the vectors don't coincide (i.e are actually the same vector) then they make up a plane, i.e coplanar.
  4. Sep 27, 2012 #3
    Yeah, it's not really meaningful to ask if two vectors are or are not coplanar. You can ask if three vectors are coplanar, however.
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