题目内容
已知点
,动点
满足
.
(1)求动点P的轨迹方程;
(2)设(1)中所求轨迹与直线
交于点
、
两点 ,求证
(
为原点)。
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824014721480807.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824014721496568.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824014721527750.png)
(1)求动点P的轨迹方程;
(2)设(1)中所求轨迹与直线
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824014721542509.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824014721574313.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824014721589315.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824014721620524.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824014721652292.png)
(1)
(2)由
得![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824014721730587.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824014721745686.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/201408240147217761411.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824014721808919.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824014721823512.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824014721854543.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824014721667529.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824014721698813.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824014721730587.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824014721745686.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/201408240147217761411.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824014721808919.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824014721823512.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824014721854543.png)
试题分析:(1)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824014721870787.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824014721901760.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824014721932961.png)
即,
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824014721667529.png)
(2)由
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824014721698813.png)
整理得,
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824014721730587.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824014721745686.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/201408240147217761411.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824014721808919.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824014721823512.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824014721854543.png)
点评:求点的轨迹方程的步骤:建立坐标系设出所求点的坐标,写出所求点的关系式,关系式坐标化整理化简,除去多余的点;第二问中直线与圆锥曲线相交时常联立方程组,将所求问题转化为与两交点坐标相关的问题
![](http://thumb.zyjl.cn/images/loading.gif)
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