1. BD is one of the diagonals of a quad ABCD .AM & CM are the perpendiculars from A & C,on BD. Show that ar(ABCD)=1/2BD(AM+CN).
2. ABCD is a trap. in which AB||CD.E is the midpoint of AD.If F is a point on BC such that segment EF is parallel to side DC, show that EF =1/2(AB+CD).