在△ABC中,角A、B、C的对边分别为a、b、c,已知B=60°,cos(B+C)=-
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.
(Ⅰ)求cosC的值;
(Ⅱ)若a=5,求△ABC的面积.
考点分析:
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;④f(x)是定义在实数集R的奇函数,且对一切x
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其中是“倍约束函数”的是
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已知平面向量
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131103102354187817446/SYS201311031023541878174012_ST/0.png)
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的夹角为60°,
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131103102354187817446/SYS201311031023541878174012_ST/2.png)
=(
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,1),|
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|=1,则|
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131103102354187817446/SYS201311031023541878174012_ST/5.png)
+2
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131103102354187817446/SYS201311031023541878174012_ST/6.png)
|=
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