ABCD is a quadrilateral in which P, Q, R and S are mid-points of the sides AB, BC, CD and DA (see figure). AC is a diagonal. Show that

(i) SR || AC and SR = \frac { 1 }{ 2 } AC

(ii) PQ = SR

(iii) PQRS is a parallelogram.

(i) SR || AC and SR = \frac { 1 }{ 2 } AC

(ii) PQ = SR

(iii) PQRS is a parallelogram.