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Vector problem

  1. Aug 28, 2005 #1
    Hi please, someone help me with those problems?

    It's about three dimension space and it is about vectors properties:

    Find the unit vectors u that are prependicular to both i+2j+k and 3i-4j+2k.

    the second is:

    Find two mutually perpendicular unit vectors that are perpendicular to 2i+3j

    Thank you for your help

  2. jcsd
  3. Aug 28, 2005 #2
    Express the vector(s) you seek in terms of unknown coefficients (e.g. ai+bj+ck) and use the definition of 'perpendicular' (i.e. the dotproduct is zero) to find equations you can solve for these unknowns.
  4. Aug 28, 2005 #3


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    Homework Helper

    You can also use the fact that the outer product (vectorial) of two vectors gives a new vector which is perpendicular to the first two. Divide by the norm to make it a unit vector.
  5. Aug 28, 2005 #4

    OK I gonna try your suggestion

  6. Aug 28, 2005 #5
    a vector perpendicular to two seperate vectors is created by using the cross product
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