[ {AE and DB bisect each other at C (Given)} ] [ {AC = EC (Definition of bisector)} ] [{2 vertical angles theorem} ] [ {D = BC (Definition of bisector)} ] [ {MACB = AECD (???) } ] [ {SAS congruence} ] What is the missing statement or reason that justifies the equality (angle MACB = angle AECD) in the proof?
