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计算:tan60°+2sin45°-2cos30°的结果是( ) A.2 B. ...
计算:tan60°+2sin45°-2cos30°的结果是( )
A.2
B.
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103000558123357286/SYS201311030005581233572003_ST/0.png)
C.
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103000558123357286/SYS201311030005581233572003_ST/1.png)
D.1
考点分析:
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在Rt△ABC中,∠C=90°,若AB=2AC,则cosA的值等于( )
A.
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B.
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如图,⊙O是Rt△ABC的外接圆,∠ABC=90°,点P是圆外一点,PA切⊙O于点A,且PA=PB.
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如图,在平面直角坐标系中,点O
1的坐标为(-4,0),以点O
1为圆心,8为半径的圆与x轴交于A,B两点,过A作直线l与x轴负方向相交成60°的角,且交y轴于C点,以点O
2(13,5)为圆心的圆与x轴相切于点D.
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2以每秒1个单位的速度沿x轴向左平移,当⊙O
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1外切时,求⊙O
2平移的时间.
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