Case I When R divides PQ internally (Fig 10 16) If R divides PQ
uuur
 such that 
RQ
m
uuur  = 
nPR
uuur ,
where m and n are positive scalars, we say that the point R divides PQ
uuur  internally in the
ratio of m : n Now  from triangles ORQ and OPR, we have
RQ
uuur  = OQ
OR
b
r
−
=
−
uuur
uuur
r
r
and
PR
uuur  = OR
OP
r
a
−
=
−
uuur
uuur
r
r ,
Therefore, we have
(
)
m b
r
−
r
r  =
(
)
n r
r−a
r     (Why