In the following figure, BL =CM. Prove that AD is a median of △ABC
In △LBDandMCD
∠BLD =∠CMD
∠LDB = ∠MDC
so, ∠DBL =∠DCM
and BL=CM
then, △LBD is congruent to △MCD [ asa congruency]
so, BD=DC [cpctc.]
therefore, AD is a median of △ABC