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Homework Help: Finding the Nonzero Vector and Area of Triangle

  1. Sep 7, 2014 #1
    1. The problem statement, all variables and given/known data

    Find a nonzero vector orthogonal to the plane through the point P, Q,and R. (b) also find the area of triangle PQR

    P(1,0,1) , Q(-2,1,3) , R(4,2,5)

    2. Relevant equations
    -Cross product
    -Finding the Angle
    -Area formula

    3. The attempt at a solution

    My steps:
    1. i found the vectors for PQ = <-3,1,2> and PR = <3,2,4>

    2. i perform the cross product (PQ X PR), which got me <0,18,-9>

    Can anyone help me?
  2. jcsd
  3. Sep 7, 2014 #2
    NVM, i just solved it!
  4. Sep 8, 2014 #3


    User Avatar
    Science Advisor

    It is a basic property of the cross product that the length of the cross product of vectors u and v is the area of the parallelogram having vectors u and v as to adjacent sides and so 1/2 the length of their cross product is the area of the triangle having u and v as sides.
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