Given: LM ∥ CB and LN ∥ CD

To prove:

In ∆ AML, LM ∥ CB

∴ By Basic proportionality theorem, we have

……….(i)

In ∆ ALN, LN ∥ CD

∴ By Basic proportionality theorem, we have

……….(ii)

By (i) and (ii), we have