For given vectors, 
ˆ
ˆ
ˆ
ˆ
ˆ
ˆ
2
2   and
a
i
j
k
b
i
j
k
=
−
+
= − +
−
r
r
, find the unit vector in the
direction of the vector a
b
+
r
r 10 Find a vector  in the direction of vector 
ˆ
ˆ
ˆ
5
2
i
j
k
−
+
 which has magnitude 8 units 11