名校
1 . 关于下列命题,正确的个数是( )
(1)若点
在圆
外,则
或
;
(2)已知圆
,直线
,则直线与圆恒相切;
(3)已知点
是直线
上一动点,
、
是圆
的两条切线,
、
是切点,则四边形
的最小面积是
;
(4)设直线系
,
中的直线所能围成的正三角形面积都等于
.
(1)若点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/43d2ff9ced79c22ff48de8357b806412.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/abce3218e8541bda1981f4e84c1d8842.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a9589f30699d1a766f1e700cc88a344.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6ed1153940c7240fb5aa358a9dc7ba09.png)
(2)已知圆
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b246d32f2c0e334968e3d610a68dc08e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac02a054bd0771a56987af33454baaea.png)
(3)已知点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d5ce1369b877ab954121015ffa229f3e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bd33764ff4efddfe11a98a609753715c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d2be49c37e30a3ced0364c3e74d8c687.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/425209ad4b273bf3eee80441e06030c6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/283b0cef5d644b8dceb910ce2c76f21c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/61128ab996360a038e6e64d82fcba004.png)
(4)设直线系
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a828c16045c333c1422c646bf01f21b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2e7dc603317eb90974c75efec9f02b1b.png)
A.![]() | B.![]() | C.![]() | D.![]() |
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