In parallelogram ABCD, points P,Q,R and S are the midpoints of sides AB,BC,CD and DA respectively.
a. (i) Prove that PQ∥SR and PS∥QR.
b. (ii) Hence, show that quadrilateral PQRS is a parallelogram.
c. (iii) Show that the area of PQRS is exactly half the area of ABCD.