AOB+BOC+COD+DOA=360°
90°+60°+50°+COD=360°
200°+COD=360°
COD=160°
ABC+CBD+DBE+EBA=360°
ABC=EBA-2°
CBD=EBA-4°
DBE=EBA-6°
EBA-2+EBA-4+EBA16+EBA=360
4EBA-12=360
4EBA=360-12
4EBA=348
EBA=348:4
EBA =87
ABC=87-2=85
CBD=87-4=83
DBE=87-6=81
