If a line intersects sides AB and AC of a ā³ABC at D and E respectively and is parallel to BC, then ADAB = AEx Then x is BC.
DE∥ BC
So, ADDB = AEEC
Or, DBAD = ECAE
Adding 1 on both sides:
We get, ABAD = ACAE.
Hence, ADAB = AEAC.
Therefore x = AC.