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已知向量与的夹角为120°,,则等于( ) A.5 B.4 C.3 D.1
已知向量
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101231646788199896/SYS201311012316467881998004_ST/0.png)
与
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101231646788199896/SYS201311012316467881998004_ST/1.png)
的夹角为120°,
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101231646788199896/SYS201311012316467881998004_ST/2.png)
,则
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101231646788199896/SYS201311012316467881998004_ST/3.png)
等于( )
A.5
B.4
C.3
D.1
考点分析:
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