Question
ΔABC and ΔABD are two triangles on the same base AB. If line segment CD is bisected by AB at O, show that ar (ΔABC) = ar (ΔABD).

Solution
Given: BD is one of the diagonals of a quadrilateral ABCD. AM and CN are perpendiculars from A and C respectively on BD.
To Prove: ar(quad. ABCD)
Proof: ar(quad ABCD)
| Area of a triangle =
x Base X Corresponding altitude