在△ABC中,BP平分∠ABC,CP平分∠ACD,试探究∠A与∠BPC之间的关系

∵∠A+∠ABC+∠ACB＝180∴∠ABC+∠ACB＝180-∠A∵∠ACD＝180-∠ACB,CP平分∠ACD∴∠PCD＝∠ACD/2＝（180-∠ACB）/2＝90-∠ACB/2∵BP平分∠ABC∴∠PBC＝∠ABC/2∵∠PCD是△PBC的外角∴∠PCD＝∠BPC+∠PBC＝∠BPC+∠AB...