如图,已知O为△ABC的外心,a,b,c分别是角A、B、C的对边,且满足
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131103100529079813495/SYS201311031005290798134027_ST/0.png)
.
(Ⅰ)证明:2a
2=b
2+c
2;
(Ⅱ)求
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131103100529079813495/SYS201311031005290798134027_ST/1.png)
的值.
考点分析:
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![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131103100529079813495/SYS201311031005290798134026_ST/1.png)
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![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131103100529079813495/SYS201311031005290798134025_ST/0.png)
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(Ⅱ)f(x)的单调递增区间;
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![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131103100529079813495/SYS201311031005290798134025_ST/1.png)
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![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131103100529079813495/SYS201311031005290798134024_ST/5.png)
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