证明：∵O为三角形ABC的内心∴AD平分∠BAC,CO平分∠ACB∴∠BAD＝∠CAD,∠ACO＝∠BCO∴弧BD＝弧CD∴BD＝CD∵∠BAD、∠BCD所对应圆弧都为劣弧BD∴∠BCD＝∠BAD∴∠BCD＝∠CAD∵∠DCO＝∠BCD+∠BCO,∠DOC＝∠CAD+∠ACO...