(1)证明:连接,则,.········ 1分
是的切线,
··········· 2分
平分······ 4分 (2)①连结,为直径, 又由(1)知············· 6分 ····························· 7分
, ··························· 8分 ②在中, ···························· 9分
················ 10分 ························ 11分 ··················· 12分 |