In a right △ABC, a perpendicular BD is drawn on to the largest side from the opposite vertex. Which of the following does not give the ratio of the areas of △ABD and △ACB?
(ABAD)2
Consider ΔABD and ΔACB:
∠BAD = ∠BAC [common angle]
∠BDA = ∠ABC [ 90∘]
By AA similarity criterion,
△ ABD ~ △ACB
Hence,
ar(ΔABD)ar(ΔACB)=(ABAC)2=(ADAB)2=(BDCB)2