Find an equation of the plane that passes through the points
     Find an equation of the plane that passes through the points P, Q, and R.  P(3, 1/3, -9), Q(2, 2/3, -3), R(5, 0, 1)  ______________ 
  
  Solution
We have two vectors from these points:
PQ = OQ - OP = ( -1 , 1/3 , 6)
PR = OR - OP = ( 2 , -2/3 , 4 )
Cross Product : PQ x PR = (16/3 , 16 , 0)
equation of plane : ax +by +cz = d where (a, b, bc) is the normal vector
a = 16/3 , b = 16 , c=0
So, 16x/3 + 16y = d.Plug ( 3, 1/3 , -9) to get d
(16/3)*3 + 16(1/3) = d
d = 16 +16/3 = 64/3
So, 16x/3 + 16y - 64/3
16x + 48y - 64 =0 (Equation of Plane)

