
(a) Bisectors of an angle between the line
and
are given
by
+ sign give internal bisector and – sign gives external bisector.
, ± representing internal and external division.
(i) Vector equation of the straight line passing through origin and parallel to
is given by
, t being scalar.
(ii) Passing through the point whose position vector
and parallel to the vector
is given by
, t being scalar.
(iii) Passing through the points whose position vector are
and
is
, t being scalar.
Equation of a plane passing through
and having a normal vector
is given as
= 0.
Note that the plane ax + by + cz + d = 0 has a normal vector as
.
(i) Perpendicular distance of the line
from the point P (PV being
) is
.
(ii) Perpendicular distance of the plane
from the point p (pv
)
=
.
The condition that two lines
and 
are coplanar is 
The shortest distance between two non-intersecting lines (Skew lines).
and
is given by
.
