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已知向量与向量的夹角为120°,若向量=+,且,则的值为 .
已知向量
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025123504839971373/SYS201310251235048399713011_ST/0.png)
与向量
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025123504839971373/SYS201310251235048399713011_ST/1.png)
的夹角为120°,若向量
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025123504839971373/SYS201310251235048399713011_ST/2.png)
=
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025123504839971373/SYS201310251235048399713011_ST/3.png)
+
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025123504839971373/SYS201310251235048399713011_ST/4.png)
,且
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025123504839971373/SYS201310251235048399713011_ST/5.png)
,则
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025123504839971373/SYS201310251235048399713011_ST/6.png)
的值为
.
考点分析:
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