e , in triangle ABC (Fig 10 8 (ii)), we have
AB
BC
+
uuur
uuur  = AC
uuur
Now again, since AC
CA
= −
uuur
uuur
, from the above equation, we have
AB
BC
CA
+
+
uuur
uuur
uuur
 = AA
0
=
uuur
r
This means that when the sides of a triangle are taken in order, it leads to zero
resultant as the initial and terminal points get coincided (Fig 10 8(iii))