1 . 抛物线的弦与在弦两端点处的切线所围成的三角形被称为“阿基米德三角形”.对于抛物线C:
给出如下三个条件:①焦点为
;②准线为
;③与直线
相交所得弦长为2.
(1)从以上三个条件中选择一个,求抛物线C的方程;
(2)已知
是(1)中抛物线的“阿基米德三角形”,点Q是抛物线C在弦AB两端点处的两条切线的交点,若点Q恰在此抛物线的准线上,试判断直线AB是否过定点?如果是,求出定点坐标;如果不是,请说明理由.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4cf210c8c9e83e70f2d3ede1e18a5f3d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/004cf3e8335136acc770de0c525cae47.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/eb70fdf064b9193e506ca43f4672af56.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3397d5c5786431a89d2a617766ca92f2.png)
(1)从以上三个条件中选择一个,求抛物线C的方程;
(2)已知
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8b17f20c25bb16153b5f2d25062ed7a7.png)
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2 . 已知抛物线
,过点
的动直线与
交于点
,且
为定值.
(1)求
的方程![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5e1d918e7fb74176679d526cdfc8fa16.png)
(2)若抛物线
在点
处的切线交于点
,求证:
①点
在定直线上![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5e1d918e7fb74176679d526cdfc8fa16.png)
②若
为
的焦点,则
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0c70ed42299c41bda5350dd3f026f523.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ea666869a508a9caa58c89903f811261.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0ae6f48b9a53c0155a692509cf31f7e6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e0dd672a03d24aa460b60a29bc685641.png)
(1)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5e1d918e7fb74176679d526cdfc8fa16.png)
(2)若抛物线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0ae6f48b9a53c0155a692509cf31f7e6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/acc290b44635265137fdf13146b6a6d9.png)
①点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/acc290b44635265137fdf13146b6a6d9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5e1d918e7fb74176679d526cdfc8fa16.png)
②若
![](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/888c3a298b0804b4272b23c4ff6e8f9d.png)
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3 . 已知点A,B是抛物线x2=2py(p为常数且p>0)上不同于坐标原点O的两个点,且
.
(1)求证:直线AB过定点;
(2)过点A、B分别作抛物线的切线,两切线相交于点M,记
OMA、
OAB、
OMB的面积分别为S1、S2、S3;是否存在定值
使得
=
S1S3?若存在,求出
值;若不存在,请说明理由.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1695034a4c212e5568fe41625fd2a417.png)
(1)求证:直线AB过定点;
(2)过点A、B分别作抛物线的切线,两切线相交于点M,记
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ce4cba95fc7d4853a243f8e3fb20ce70.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ce4cba95fc7d4853a243f8e3fb20ce70.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ce4cba95fc7d4853a243f8e3fb20ce70.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/df64046e91b047037f19e4032e3b6de3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7c42e278b09e6ad8956418c47463a376.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/df64046e91b047037f19e4032e3b6de3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/df64046e91b047037f19e4032e3b6de3.png)
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