1 . 设点
在直线
上运动,过点
作圆
的切线,切点为
,则切线长
的最小值是______ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/aa6342e0a5a8942cfb1cf535ceb2c50d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a353d1a988596880c0a48c2303d20c2c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d063ec7f9dbeba72fabf4437f9400e07.png)
您最近一年使用:0次
2 . 从点
向
引切线
,
,其中
为切点,则![](https://staticzujuan.xkw.com/quesimg/Upload/formula/88bee8e70f1fab639be1636c7bce0477.png)
___________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/88aa54f855334cab19d8d19ca9aea9dd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7c3a9b723303acf1669d4d88a7172b99.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/2fb398137779190b35492d9f06d5fbc3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/88bee8e70f1fab639be1636c7bce0477.png)
您最近一年使用:0次
3 . 设
为实数,若
,则
的取值范围为____ .
![](https://img.xkw.com/dksih/QBM/2016/4/8/1572580955979776/1572580961624064/STEM/b2462d4628c741b98b1aa68934153aa5.png?resizew=17)
![](https://img.xkw.com/dksih/QBM/2016/4/8/1572580955979776/1572580961624064/STEM/45f1a6d2ecf84318bbefa1779aee67b0.png?resizew=376)
![](https://img.xkw.com/dksih/QBM/2016/4/8/1572580955979776/1572580961624064/STEM/b2462d4628c741b98b1aa68934153aa5.png?resizew=17)
您最近一年使用:0次
4 . 设圆O:
,直线l:x+3y-8=0,点A∈l,使得圆O上存在点B,且∠OAB=30°(O为坐标原点),则点A的横坐标的取值范围是________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ed1c0bac87cd65fe5eaabeefd5e33ad8.png)
您最近一年使用:0次