r
r
a
a  is not a null vector, then
|
| |
||
|
a
a
λ
r= λ
r  =
1 |
| 1
|
a| a
r
r
© NCERT
not to be republished
VECTOR ALGEBRA
433
So, λ ar  represents the unit vector in the direction of ar We write it as
ˆa  =
|1
| a
a
r
r
�Note  For any scalar k, 0 = 0 k
r
r
10 5