If BC = BA (since B is the midpoint) and m bisects BC, that means that
BE = EC. In addition, since l bisects BA and D is the connecting point, that means that BD=DA. That also means that BD+DA=AB and AB=CB, so BD+BD=AB=CB, and 2*BD=CB , making BD=CB/2=AD. In addition, since EC is CD/2, EC=AD. For AB and BE, since AB=CB and BE=BC=CD/2, BE=AB/2