, μ =
221
−
Example 30 If with reference to the right handed system of mutually perpendicular
unit vectors 
ˆ
ˆ
ˆ ˆ
ˆ
ˆ
ˆ
ˆ
,
 and ,
3
,  
2
– 3
i
j
k
i
j
i
j
k
α =
−
β =
+
r
r
, then express β
r  in the form
1
2
, where  1
   
  
 
r
r
r
r
is parallel to 
  and  2
r
r
 is perpendicular to αr Solution Let 
1
   ,  
 
r
r
 is a scalar, i e , 
1
ˆ
ˆ
3 i
rβ = λ − λj