1 . 如图,延长△ABC的角平分线AD交其外接圆于E,若AD =AB= 1,DE =
,则AC=_________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cf298f00799cbf34b4db26f5f63af92f.png)
![](https://img.xkw.com/dksih/QBM/2015/6/16/1572126201487360/1572126207524864/STEM/460448641459437db3c1fec97ab5ba10.png?resizew=144)
您最近一年使用:0次
2 . (选修4-1:几何证明选讲)如图,已知直线
切圆
于点
,直线
交圆
于点
、
,若
,
,则圆
的半径长为________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ff8513b61617aa6b19ad2a764ee3aeae.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f97e22c9dd88a2510de9e5a309191934.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0e2868b617c871e18c928c9a573bc8c7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bec08679eab52e3a0013abecdd1e6cc3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f97e22c9dd88a2510de9e5a309191934.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/49de2536004d4f0819e781fffca41a2a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ca66a268d6f46e0e9d5d9151b785be60.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ad4b3ac161685fc1c03f5591b3ccc1d4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dc17edc472b148dc491f978333d3bdee.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f97e22c9dd88a2510de9e5a309191934.png)
![](https://img.xkw.com/dksih/QBM/2015/3/30/1572047081906176/1572047087263744/STEM/3226845ff076414f97aabeceed7ba595.png?resizew=160)
您最近一年使用:0次
2012·宁夏银川·一模
3 . 如图,A,B,C,D四点在同一圆上,
与
的延长线交于点
,点
在
的延长线上.
![](https://img.xkw.com/dksih/QBM/2014/10/29/1571885855260672/1571885860954112/STEM/dbe84fa9a7234eecb3542d045f576190.png)
(1)若
,求
的值;
(2)若
,证明:
.
![](https://img.xkw.com/dksih/QBM/2014/10/29/1571885855260672/1571885860954112/STEM/3959f0469da944df9869dc3fc5c0c0f0.png)
![](https://img.xkw.com/dksih/QBM/2014/10/29/1571885855260672/1571885860954112/STEM/e0bea0a27c90469b8eac6942c0c7301a.png)
![](https://img.xkw.com/dksih/QBM/2014/10/29/1571885855260672/1571885860954112/STEM/b6dc0f1e71d74eb9a6a9f2bf2884d5eb.png)
![](https://img.xkw.com/dksih/QBM/2014/10/29/1571885855260672/1571885860954112/STEM/5ce69915a36b4da19860d4b41c0ad358.png)
![](https://img.xkw.com/dksih/QBM/2014/10/29/1571885855260672/1571885860954112/STEM/2a007b253c644618b8bbe16c5741a2b9.png)
![](https://img.xkw.com/dksih/QBM/2014/10/29/1571885855260672/1571885860954112/STEM/dbe84fa9a7234eecb3542d045f576190.png)
(1)若
![](https://img.xkw.com/dksih/QBM/2014/10/29/1571885855260672/1571885860954112/STEM/065225e99266493081e4c369273fc8e5.png)
![](https://img.xkw.com/dksih/QBM/2014/10/29/1571885855260672/1571885860954112/STEM/785220f916254bce9c3c65e2bd7be08d.png)
(2)若
![](https://img.xkw.com/dksih/QBM/2014/10/29/1571885855260672/1571885860954112/STEM/74858fd5b2314c268aff8a3a49676f3b.png)
![](https://img.xkw.com/dksih/QBM/2014/10/29/1571885855260672/1571885860954112/STEM/995d49f3b9b74862b7817e5b93a1ef3b.png)
您最近一年使用:0次