Diagonals AC and BD of a trapezium ABCD with AB || DC intersect each other at O.Then
Triangles on the same base and between same parallels are equal in area.
Hence, Area of Δ ADC = Area of Δ BDC
⇒ Area of Δ AOD + Area of Δ DOC
= Area of Δ BOC + Area of Δ DOC
⇒ Area of Δ AOD = Area of Δ BOC