解题方法
1 . 设A,B为拋物线C:
上两个不同的点,且直线
过抛物线
的焦点
,分别以A,B为切点作抛物线
的切线,两条切线交于点
.则下列结论:
①点
一定在拋物线
的准线上;
②
;
③
的面积有最大值无最小值.
其中,正确结论的个数是( )
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/344ccbf79da6ad7e3709d6fa72efb756.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
①点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
②
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c80406e8beb743b122bd7b021671c780.png)
③
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/68c6aaf588fa1a15127568c78c39e8eb.png)
其中,正确结论的个数是( )
A.0 | B.1 | C.2 | D.3 |
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