连接AO并延长AO交圆于D,连接BD、CD∵直径AD∴∠ABD＝∠ACD＝90,AB＝2R＝2∵AB＝√3,AC＝√2∴cos∠BAD＝AB/AD＝√3/2,cos∠CAD＝AC/AD＝√2∴∠BAD＝30,∠CAD＝45∴当AB、AC位于直径AD的两侧时∠BAC＝∠BAD+∠CAD＝7...