Prove that the line joining the mid-points of the diagonals of a trapezium is parallel to the parallel sides of the trapezium.
Given: Let ABCD be a trapezium in which and let M and N be the mid-points of diagonals AC and BD.
To Prove:
Proof: Join CN and produce it to meet AB at E
In and we have
DN = BN {N is the mid-point of BD}
{alternate interior angle}
{alternate interior angles}
DC = EB and CN = NE {by CPCT}
Thus , the points M and N are the mid-points of AC and CE, respectively.
{By mid-point theorem}
Hence Proved