Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

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


    User Avatar
    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.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook