© NCERT
not to be republished
 MATHEMATICS
460
� The vector sum of two coinitial vectors is given by the diagonal of the
parallelogram whose adjacent sides are the given vectors � The multiplication of a given vector by a scalar λ, changes the magnitude of
the vector by the multiple |λ|, and keeps the direction same (or makes it
opposite) according as the value of λ is positive (or negative) � For a given vector ar , the vector ˆ
|
a|
a
=a
r
r  gives the unit vector in the direction
of ar � The position vector of a point R dividing a line segment joining the points
P and Q whose position vectors are 
aand
rb
r
 respectively, in the ratio m : n
(i)
internally, is given by na
mmb
+n
+
r
r