命题“∃x∈R,x2+1<0”的否定形式是 .
考点分析:
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在△ABC中,a=25,b=10,∠A=60°,则cosB=
.
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已知
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=(1,2,3),
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=(2,1,2),
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=(1,1,2),点Q在直线OP上运动,则当
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取得最小值时,点Q的坐标为( )
A.
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B.
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C.
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D.
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若△ABC中,∠C=90°,A(1,2,-3k),B(-2,1,0),C(4,0,-2k),则k的值为( )
A.
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B.-
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C.2
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D.±
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若直线y=kx+2与双曲线x
2-y
2=6的右支交于不同的两点,则k的取值范围是( )
A.
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,
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B.
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101231638043872335/SYS201311012316380438723009_ST/2.png)
C.
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101231638043872335/SYS201311012316380438723009_ST/3.png)
D.
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设圆C的圆心在双曲线
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101231638043872335/SYS201311012316380438723008_ST/0.png)
-
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=1(a>0)的右焦点且与此双曲线的渐近线相切,若圆C被直线l:x-
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101231638043872335/SYS201311012316380438723008_ST/2.png)
y=0截得的弦长等于2,则a的值为( )
A.
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B.
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C.2
D.3
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