11-12高三下·吉林长春·开学考试
1 . 如图,
是⊙O的直径 ,
是⊙O的一条弦 ,
的平分线
交⊙O于点
,
⊥
,且
交
的延长线于点
,
交
于点
.
![](https://img.xkw.com/dksih/QBM/2012/2/27/1570777179717632/1570777185271808/STEM/3b3433391b2c440da8318c8876df0326.png?resizew=170)
(1)求证:
是⊙O的切线;
(2)若
求
的值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b79dd200766db27fb90d6bd1992cf658.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e1a9c6a736e6eac98a676fa3232db5a5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/146a63bac5ecd239f2696801e8eaa0b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/88929f4ba0851730d5f941d426b87548.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1a6c6e7c025362c46a64a8956761f08e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e1a9c6a736e6eac98a676fa3232db5a5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1a6c6e7c025362c46a64a8956761f08e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e1a9c6a736e6eac98a676fa3232db5a5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/598c4ff9fc8518fa4829e39254d3f6e5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/88929f4ba0851730d5f941d426b87548.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://img.xkw.com/dksih/QBM/2012/2/27/1570777179717632/1570777185271808/STEM/3b3433391b2c440da8318c8876df0326.png?resizew=170)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1a6c6e7c025362c46a64a8956761f08e.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4cf15c3996b448091009190d54df2eaa.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/78d55c6aec1956ca8ca99d0518e2b36e.png)
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10-11高二下·吉林·开学考试
2 . 下列判断正确的是( )
A.两个直角三角形相似 | B.两个相似三角形一定全等 |
C.凡等边三角形都相似 | D.所有等腰三角形都相似 |
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