如图,在平面直角坐标系xOy中,已知抛物线
的焦点为F,准线与x轴的交点为H,过点F的直线l与抛物线的交点为A,B,且
.
求证:
;
求
的值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/661bd8d4d82205bd311e7349ae91f602.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/19525606adc4a20afdadbc38a1f195a0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4141b26d2c32655003494a91ad6331b5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7a4bc86f1590550f5c4de5b98a8ceafd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/65863c1abad833b79c303bfca24f535c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8cb6a7c8fcb371b2124abcabcb374d88.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/9/60c133c1-a044-4f14-8a31-94496e1a3292.png?resizew=147)
更新时间:2019-03-18 15:11:18
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【知识点】 抛物线中的定值问题
相似题推荐
解答题-问答题
|
适中
(0.65)
解题方法
【推荐1】如图,已知抛物线
直线
交抛物线C于A,B两点,O为坐标原点.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/26/367645c0-562b-405c-8670-f5d46c8a6b6f.png?resizew=141)
(1)证明:
;
(2)设抛物线C在点A处的切线为
,在点B处的切线为
,证明:
与
的交点M在一定直线上.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/496e5f255a3778112eaedee8e06c6e70.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/02ebce8b2a915356ed39f36c5bad2ebe.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/26/367645c0-562b-405c-8670-f5d46c8a6b6f.png?resizew=141)
(1)证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3825ccc273ef9a672a606432d165b866.png)
(2)设抛物线C在点A处的切线为
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2e9b0f5f44abbc6544a2f672b025b013.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3f6f17bc385bafb37e8f964e5eb99cd0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2e9b0f5f44abbc6544a2f672b025b013.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3f6f17bc385bafb37e8f964e5eb99cd0.png)
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解答题-证明题
|
适中
(0.65)
解题方法
【推荐2】已知直线
过抛物线
的焦点,且垂直于抛物线的对称轴,
与抛物线两交点间的距离为2.
(1)求抛物线
的方程;
(2)若点
,过点
的直线
与抛物线
相交于
两点,设直线
的斜率分别为
.求证:
为定值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0f85fca60a11e1af2bf50138d0e3fe62.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/82ea1be9b9b6bb12afa7e1ce703d1603.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0f85fca60a11e1af2bf50138d0e3fe62.png)
(1)求抛物线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
(2)若点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a7bd4e5049fa304e4d352bfe6dee455d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4842c7c85e9610baedc948a41107d5e2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/294f5ba74cdf695fc9a8a8e52f421328.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/01c74a907dda6bb7d9d56d009d9df253.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/790ef3382b1c731f2885eecfd92c2a86.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/90963760acac7bfad3ae03088c6c80b0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6b881044b5c73db6fcce110525741b02.png)
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