如图,已知角C0B＝2倍角A0C,0D平分角A0B,且角C0D＝19度,求角A0B

∵OD平分∠AOB ∴∠BOD=∠AOD ∵∠COB=2∠AOC ∴∠BOD+∠COD=2∠AOC ∵∠AOC=∠AOD-∠COD 又∵∠COD=19° ∴∠BOD+∠COD=2(∠AOD-∠COD) ∴∠BOD=∠AOD=3∠COD=57° ∴∠AOB= 2∠BOD=114°