�Note    From Fig 10 9, using the triangle law, one may note that
OA
AC
+
uuur
uuur  = OC
uuur
or
OA
OB
+
uuur
uuur  = OC
uuur                                 (since AC
uuur=OB
uuur
)
which is parallelogram law Thus, we may say that the two laws of vector
addition are equivalent to each other Properties of vector addition
Property 1 For any two vectors 
aand
rb
r
,
a
b
+
r
r
 = b
a
+
r
r
(Commutative property)
Fig 10