Taking as origin,
let the position vectors
of A, B and C be a, b
and c respectively so
that those of I), E and
F are a+b, b+c, c+a
respectively and that
of G is a+b+c.
If M! be the mid. point of diagonal OG, then M t is
a+b+c
If Af 2 be the mid. point of diagonal AE and M 2 is
a+b+c { e M
Similarly mid. point of other diagonals DC and BF is
also the point whose position vector is .
4
Again mid. point L of BD is J (b+a+b)=s* ~
and mid. point M of CF is 
/. mid. point G of LM is i
