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在某项体育比赛中,七位裁判为一选手打出的分数如下: 90 89 90 95 93...
在某项体育比赛中,七位裁判为一选手打出的分数如下:
90 89 90 95 93 94 93
去掉一个最高分和一个最低分后,所剩数的平均值和方差分别为( )
A.92,2
B.92,2.8
C.93,2
D.93,2.8
考点分析:
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A.
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B.
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C.
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D.
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平面向量
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131103100038701123746/SYS201311031000387011237004_ST/0.png)
与
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131103100038701123746/SYS201311031000387011237004_ST/1.png)
的夹角为
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131103100038701123746/SYS201311031000387011237004_ST/2.png)
,若
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131103100038701123746/SYS201311031000387011237004_ST/3.png)
,
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131103100038701123746/SYS201311031000387011237004_ST/4.png)
,则
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131103100038701123746/SYS201311031000387011237004_ST/5.png)
=( )
A.
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131103100038701123746/SYS201311031000387011237004_ST/6.png)
B.
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131103100038701123746/SYS201311031000387011237004_ST/7.png)
C.4
D.12
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a,b,c表示直线,M表示平面,给出下列四个命题:
①若a∥M,b∥M,则a∥b;
②若b⊂M,a∥b,则a∥M;
③若a⊥c,b⊥c,则a∥b;
④若a⊥M,b⊥M,则a∥b.
其中正确命题的个数有( )
A.0个
B.1个
C.2个
D.3个
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已知向量
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131103100038701123746/SYS201311031000387011237002_ST/0.png)
,则下列选项中与
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131103100038701123746/SYS201311031000387011237002_ST/1.png)
共线的一个向量为( )
A.(1,2)
B.(1,4)
C.
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131103100038701123746/SYS201311031000387011237002_ST/2.png)
D.
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如果sinx+cosx=-
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,且0<x<π,那么cotx的值是( )
A.-
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B.-
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或-
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C.-
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D.
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131103100038701123746/SYS201311031000387011237001_ST/5.png)
或-
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