If 
and 
respectively are the position vectors of points A, B, C and D, then find the angle between the straight lines 
and 
. Find whether 
and 
are collinear or not.
If the position vectors of two points on a line, 
and 
, are given then the direction ratios of the line are given by x2-x1, y2-y1, z2-z1.
Given that the position vectors of points A, B, C and D respectively are 
and 
. Then the direction ratios of line 
are 1, 4, -1 and the direction ratios of line 
are -2, -8, 2.
If the direction ratios of two lines are given, a1, a2, a3 and b1, b2, b3, then the angle between the lines, θ, is given by:
= -1
hence θ= 180°.
and 
are collinear. 1