Question

In a trapezium ABCD, it is given that AB║CD and AB = 2CD. Its diagonals AC and BD intersect at the point O such that ar(∆AOB) = 84cm² . Find ar(∆COD).

Answer 1

In ∆AOB and ∆COD, we have:

∠AOB = ∠COD (vertically opposite angle) 

∠OAB = ∠OCD ( alternate angles as AB ǁ CD) 

Applying AA similarity criterion, we get : 

∆ AOB - ∆COD