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设向量,满足:||=1,||=2,•(+)=0,则与的夹角是( ) A.30° ...
设向量
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,
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满足:|
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101231447058288972/SYS201311012314470582889002_ST/2.png)
|=1,|
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|=2,
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•(
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+
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)=0,则
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与
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的夹角是( )
A.30°
B.60°
C.90°
D.120°
考点分析:
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![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101231447058161023/SYS201311012314470581610018_ST/images0.png)
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![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101231447058161023/SYS201311012314470581610017_ST/images0.png)
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![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101231447058161023/SYS201311012314470581610017_ST/0.png)
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