M: May I know your e-mail addressW: I’ll send you an e-mail, so we don’t have to do the spelling on the phone, OKM: That’s a good idea. What are the two speakers doing（）。 A: Sending an e-mail. B: Doing spelling exercise. C: Chatting online. D: Talking on the phone.
M: May I know your e-mail addressW: I’ll send you an e-mail, so we don’t have to do the spelling on the phone, OKM: That’s a good idea. What are the two speakers doing（）。 A: Sending an e-mail. B: Doing spelling exercise. C: Chatting online. D: Talking on the phone.
.如图，过圆O外一点M作它的k*s#5^u一条切线，切点为A，过A作直线AP垂直直线OM，垂足为P.（1）证明：OM·OP=OA2；（2）N为线段AP上一点，直线NB垂直直线ON，且交圆O于B点.过B点的k*s#5^u切线交直线ON于K.证明：∠OKM=90°.
.如图，过圆O外一点M作它的k*s#5^u一条切线，切点为A，过A作直线AP垂直直线OM，垂足为P.（1）证明：OM·OP=OA2；（2）N为线段AP上一点，直线NB垂直直线ON，且交圆O于B点.过B点的k*s#5^u切线交直线ON于K.证明：∠OKM=90°.
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