sankar basu

In triangle ABC, Let D be the foot of the perpendicular drawn from B onto the opposite side AC. Then, is it that the ratio's AB / BC = AD / DC = <ABD/<DBC ? I presume it is true. But, can one suggest an analytical proof of this theorem ? Or state otherwise the reason (if it is not true). It would be of much help. - Thanks and regards Sankar Basu Post Doc Bioinformatics Linkoping University, Sweden