题目内容
(12分)已知
,
分别是双曲线
的左右焦点,以坐标原点
为圆心,以双曲线的半焦距
为半径的圆与双曲线在第一象限的交点为
,与
轴正半轴的交点为
,点
在
轴上的射影为
,且![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823143941296436.gif)
.
⑴求双曲线的离心率;
⑵若
交双曲线于点
,且
,求
.
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823143940703208.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823143940828206.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823143940859719.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823143941000203.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823143941000132.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823143941078197.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823143941202192.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823143941218202.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823143941078197.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823143941202192.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823143941296205.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823143941296436.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823143941312242.gif)
⑴求双曲线的离心率;
⑵若
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823143941358232.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823143941374319.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823143941390499.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823143941405187.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823143941421294.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823143941436616.gif)
解:⑴由已知
,
,
…1分 ∵
∴
,
∵A在双曲线
上 ∴
…4分.
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/201408231439417021666.gif)
,
…6分
⑵∵
∴
…8分
由
,
都在双曲线
上,
得![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/201408231439422791529.gif)
…10分
由⑴得
代入⑵
…12分
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823143941452312.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823143941468303.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823143941483307.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823143941499622.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823143941514409.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823143941530537.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823143941670484.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823143941686535.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/201408231439417021666.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823143941873555.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823143941889536.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823143941998473.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823143942014326.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823143941421294.gif)
⑵∵
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823143941390499.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823143942216864.gif)
由
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823143941078197.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823143941374319.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823143941670484.gif)
得
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/201408231439422791529.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/2014082314394232673.gif)
由⑴得
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823143942341458.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823143942372890.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823143941436616.gif)
![](http://thumb.zyjl.cn/images/loading.gif)
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