Answer with explanation:
In Trapezoid A B CD, having legs AB and CD. it is also given that Diagonals AC and B D intersect each other at O.
In a trapezium one pair of Opposite sides are parallel.
That is , AD ║ BC.
→→Area(ΔABD)=Area(ΔACD)
→Triangles on the same base and between the same parallel are equal in area.
→AD, is the same base of two triangles ,△A B D and △A CD and AD ║ BC.