证明：∵∠ACD＝∠A+∠ABC，CO平分∠ACD∴∠OCD＝∠ACD/2＝（∠A+∠ABC）/2∵BO平分∠ABC∴∠OBC＝∠ABC/2∴∠OCD＝∠O+∠OBC＝∠O+∠ABC/2∴∠O+∠ABC/2＝（∠A+∠ABC）/2∴∠O＝∠A/2
你的条件多没给啊
