if B is the mid point of AC and C is the mid pointof BD,where A,B,C,D lie on a straight line, prove that AB=CD.
if B is mid point of AC, then AB=BC
if C is h the mid point of BD then , BC=CD
so AB=BC=CD
SO AB=CD
if C is h the mid point of BD then , BC=CD
so AB=BC=CD
SO AB=CD