题目内容
如图,F是抛物线
的焦点,Q是准线与x轴的交点,直线
经过点Q。
(Ⅰ)直线
与抛物线有唯一公共点,求
方程;
(Ⅱ)直线
与抛物线交于A、B两点;
(i)设FA、FB的斜率分别为
,求
的值;
(ii)若点R在线段AB上,且满足
,求点R的轨迹方程。
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/201408231935181843935.jpg)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823193517778525.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823193517794280.png)
(Ⅰ)直线
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823193517794280.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823193517794280.png)
(Ⅱ)直线
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823193517794280.png)
(i)设FA、FB的斜率分别为
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823193518012458.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823193518153464.png)
(ii)若点R在线段AB上,且满足
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823193518168853.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/201408231935181843935.jpg)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/2014082319351823114681.jpg)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823193518246813.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823193518262443.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823193518278651.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823193518309983.png)
(i)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/201408231935183241660.png)
(ii)设点R的坐标为(x,y)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823193518340907.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823193518356785.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/201408231935183711226.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823193518387767.png)
由
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823193518418429.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823193518434169.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823193518434440.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823193518480421.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823193518496798.png)
综上所述,点R的轨迹为
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823193518512324.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823193518496798.png)
略
![](http://thumb.zyjl.cn/images/loading.gif)
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