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已知平面向量,满足•(+)=3,且||=2,||=1,则向量与的夹角为( ) A...
已知平面向量
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,
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满足
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025124130699573870/SYS201310251241306995738003_ST/2.png)
•(
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+
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)=3,且|
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|=2,|
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025124130699573870/SYS201310251241306995738003_ST/6.png)
|=1,则向量
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025124130699573870/SYS201310251241306995738003_ST/7.png)
与
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的夹角为( )
A.
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025124130699573870/SYS201310251241306995738003_ST/9.png)
B.
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025124130699573870/SYS201310251241306995738003_ST/10.png)
C.
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025124130699573870/SYS201310251241306995738003_ST/11.png)
D.
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025124130699573870/SYS201310251241306995738003_ST/12.png)
考点分析:
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![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025124117571507009/SYS201310251241175715070019_ST/1.png)
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![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025124117571507009/SYS201310251241175715070018_ST/0.png)
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