∠BOD=38°则∠BOC=76°∠A=0.5∠BOC=38°
∠OAB=∠OBA∠OAC=∠OCA∠OAB+∠OAC=∠OBA+∠OCA=∠A∠OBC=∠OCB∠OBC+∠OCB=180-∠BOD=142∠OAB+∠OBA+∠OAC+∠OCA+∠OBC+∠OCB=1802∠A+142=180∠A=19
