Show that the vectors 
ˆ
ˆ
ˆ
ˆ
ˆ
ˆ
ˆ
ˆ
ˆ
2
,
3
5
and 3
4
4
i
j
k i
j
k
i
j
k
−
+
−
−
−
−
 form the vertices
of a right angled triangle 18 If ar  is a nonzero vector of magnitude ‘a’ and λ a nonzero scalar, then λ ar  is unit
vector if
(A) λ = 1
(B) λ = – 1
(C) a = |λ|
(D) a = 1/|λ|
10 6