The net displacement made by the girl from
point A to the point C, is given by the vector AC
uuur  and
expressed as
AC
uuur  = AB
BC
+
uuur
uuur
This is known as the triangle law of vector addition In general, if we have two vectors ar  and b
r
 (Fig 10 8 (i)), then to add them, they
are positioned so that the initial point of one coincides with the terminal point of the
other (Fig 10 8(ii))