)
or
rr  = mb
na
m
+n
+
r
r
(on simplification)
Hence, the position vector of the point R which divides P and Q internally in the
ratio of m : n is given by
OR
uuur  = mb
na
m
+n
+
r
r
Fig 10 16
© NCERT
not to be republished
VECTOR ALGEBRA
439
Case II When R divides PQ externally (Fig 10 17) We leave it to the reader as an exercise to verify
that the position vector of the point R which divides
the line segment PQ externally in the ratio
m : n 
PR
 i