Question
Determine whether the following pair of lines intersect:
and 
Solution
The equations of two lines are
...(1)
and 
...(2)
Comparing these equations with
Let S be points on line (1) with position vector 
and T be point on line (2) with position vector 
so that
Let 
be the S.D. vector between given lines. Therefore, it is parallel to 
If 
is a unit vector along 
, then
Now S.D. = Projection of 
on 
= Projection of 
on 
= 
∴ given lines interesect.
