Find the parametric and symmetric forms of the equation of t
     Find the parametric and symmetric forms of the equation of the line that passes through the points P (1, 4, 5) and Q (3, -2, 1). 
  
  Solution
Vector passing these two points is <3-1,-2-4,1-5>= <2,-6,-4>
We can use any of the point to find the parametric equation.Lets use point P
x=1+2t , y=4-6t ,z=5-4t
Solving for t gives the symmetric equation
(x-1)/2= (y-4)/-6 = (z-5)/-4

