Diagonals AC and BD of trapezium ABCD in which AB ∥ DC, intersect each other at O. Prove that the triangle AOD is equal in area to triangle BOC.
It can be observed that ΔDAC and ΔDBC lie on the same base DC and between the same parallels AB and CD.
∴ Area (ΔDAC) = Area (ΔDBC)
⇒ Area (ΔDAC) − Area (ΔDOC) = Area (ΔDBC) − Area (ΔDOC)
⇒ Area (ΔAOD) = Area (ΔBOC)