名校
1 . 以下四个关于圆锥曲线的命题:
(1)直角坐标系内,到点
和到直线
距离相等的点的轨迹是抛物线;
(2)设
为两个定点,若
,则动点
的轨迹为双曲线;
(3)方程
的两根可分别作椭圆和双曲线的离心率;
(4)若直线
和
没有交点,则过点
的直线与椭圆
的交点个数为
.其中真命题的序号为___ .(写出所有真命题的序号)
(1)直角坐标系内,到点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b2c7b74fd862d7e3f35e40ae1f626c4c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5434dfea8a321255e5466bc60ab1be0b.png)
(2)设
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/01c74a907dda6bb7d9d56d009d9df253.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2d0ecf8049d69be4f8c15a8f35bffcf5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
(3)方程
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/67f9da93ffb16e3e15db5eb0b7a3618d.png)
(4)若直线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b29b82fcfd62228e12f020fec264fe21.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7c3a9b723303acf1669d4d88a7172b99.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/82aaa597a5aa6176863eda3fdf83e181.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6205da5e1d2730ee0b3de8bca3e29f5e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/61128ab996360a038e6e64d82fcba004.png)
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