Question

如圖2-9,MN切⊙O于點(diǎn)A,∠AOB=60°,那么∠BAM等于(    )

圖2-9

A.120°              B.90°              C.60°           D.30°

Answer 1

解析:同弧對(duì)的圓周角等于圓心角一半,而弦切角等于它所夾弧所對(duì)的圓周角,

∴∠BAM=∠AOB=30°.

答案:D