9 Find |
|
xr , if for a unit vector ar , (
) (
)
12
x
a
x
a
−
⋅
+
=
r
r
r
r 10 If 
ˆ
ˆ
ˆ
ˆ
ˆ
ˆ
ˆ
ˆ
2
2
3 ,
2
and
3
a
i
j
k
b
i
j
k
c
i
j
=
+
+
= − +
+
=
+
r
r
r
are such that a
+ λb
r
r
 is
perpendicular to cr , then find the value of λ