题目内容
在△ABC中,角A、B、C的对边分别为a、b、c,若![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823131906301796.gif)
(1)判断△ABC的形状;
(2)若
的值.
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823131906301796.gif)
(1)判断△ABC的形状;
(2)若
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823131906333345.gif)
(1)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823131906348408.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823131906364237.gif)
(1)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823131906504913.gif)
5分
即![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823131906551574.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823131906598612.gif)
为等腰三角形. 8分
(2)由(I)知
12分
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823131906660289.gif)
14分
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823131906379894.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823131906504913.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823131906535535.gif)
即
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823131906551574.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823131906567528.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823131906598612.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823131906613414.gif)
(2)由(I)知
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/201408231319066291008.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823131906660289.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823131906738244.gif)
![](http://thumb.zyjl.cn/images/loading.gif)
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