Given: In ∆ABC, L and M are two points on AB and AC, such that LM || BC.

To Prove: ar(∆LOB) = ar(∆MOC)
Proof: MB and LC intersect each other at O.
Since, ∆LBC and ∆MBC both lie on the same base BC and between the same parallel lines BC and LM
ar (∆LBC) = ar (∆MBC)
⇒ ar (∆LOB) + ar (∆BOC) = ar(∆MOC) + ar(∆BOC)
⇒ ar (∆LOB) = ar (∆MOC)
[Eliminating ar (∆BOC) from both sides]
Hence proved.