1 . 已知四边形
为圆
的内接四边形,且
,其对角线
与
相交于点
.过点
作圆
的切线交
的延长线于点
.
![](https://img.xkw.com/dksih/QBM/2016/6/1/1572683042848768/1572683049271296/STEM/eba0a85b01e443c2872a5fca74406206.png)
(I)求证:
;
(II)若
,求证:
.
![](https://img.xkw.com/dksih/QBM/2016/6/1/1572683042848768/1572683049271296/STEM/c1aed038f3534498a437fe4656651362.png)
![](https://img.xkw.com/dksih/QBM/2016/6/1/1572683042848768/1572683049271296/STEM/6884ebf765214e92a3e51ec95c828f57.png)
![](https://img.xkw.com/dksih/QBM/2016/6/1/1572683042848768/1572683049271296/STEM/04aba819001943faa0f602bf04b52fcb.png)
![](https://img.xkw.com/dksih/QBM/2016/6/1/1572683042848768/1572683049271296/STEM/c64b71f098554966b9f0db23c34d8d4e.png)
![](https://img.xkw.com/dksih/QBM/2016/6/1/1572683042848768/1572683049271296/STEM/686b6e79fc4f48168df06a59eec23ad7.png)
![](https://img.xkw.com/dksih/QBM/2016/6/1/1572683042848768/1572683049271296/STEM/0969e595ed0f4cf5b40bb168819e5c0f.png)
![](https://img.xkw.com/dksih/QBM/2016/6/1/1572683042848768/1572683049271296/STEM/e9872bc905294bfa87593165c3dba318.png)
![](https://img.xkw.com/dksih/QBM/2016/6/1/1572683042848768/1572683049271296/STEM/6884ebf765214e92a3e51ec95c828f57.png)
![](https://img.xkw.com/dksih/QBM/2016/6/1/1572683042848768/1572683049271296/STEM/f1f9a96b87df4ef8840213699c1cb76d.png)
![](https://img.xkw.com/dksih/QBM/2016/6/1/1572683042848768/1572683049271296/STEM/575ee7c8e9b1459088170c982ef5995d.png)
![](https://img.xkw.com/dksih/QBM/2016/6/1/1572683042848768/1572683049271296/STEM/eba0a85b01e443c2872a5fca74406206.png)
(I)求证:
![](https://img.xkw.com/dksih/QBM/2016/6/1/1572683042848768/1572683049271296/STEM/8b7ee8d20a934c459254b2c1545bc938.png)
(II)若
![](https://img.xkw.com/dksih/QBM/2016/6/1/1572683042848768/1572683049271296/STEM/68e8fe3a01f3491cb934548f68708c70.png)
![](https://img.xkw.com/dksih/QBM/2016/6/1/1572683042848768/1572683049271296/STEM/0e0ebf40db8942f69c7673c7643690f3.png)
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2 . 与直线
和圆
都相切的半径最小的圆的方程是___________
![](https://img.xkw.com/dksih/QBM/2011/8/17/1570286949228544/1570286954348544/STEM/2e770812f7124ae2aeb971dc2e38e386.png?resizew=77)
![](https://img.xkw.com/dksih/QBM/2011/8/17/1570286949228544/1570286954348544/STEM/064c213e4a514698b2a98dae7ed2752b.png?resizew=128)
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10-11高二下·河南郑州·阶段练习
3 . .选修4-1:几何证明选讲
已知
ABC中,AB=AC, D是
ABC外接圆劣弧AC弧上的点(不与点A,C重合),延长BD至E.
(1)求证:AD的延长线平分
CDE;
(2)若
BAC=30°,
ABC中BC边上的高为2+
,
求
ABC外接圆的面积.
已知
![](https://img.xkw.com/dksih/QBM/2012/3/22/1570818204868608/1570818210324480/STEM/b18484264a8a4d4b96a55e77f757e548.png)
![](https://img.xkw.com/dksih/QBM/2012/3/22/1570818204868608/1570818210324480/STEM/b18484264a8a4d4b96a55e77f757e548.png)
(1)求证:AD的延长线平分
![](https://img.xkw.com/dksih/QBM/2012/3/22/1570818204868608/1570818210324480/STEM/fb0457dd18ff453aa76a046a9e445e0a.png)
(2)若
![](https://img.xkw.com/dksih/QBM/2012/3/22/1570818204868608/1570818210324480/STEM/fb0457dd18ff453aa76a046a9e445e0a.png)
![](https://img.xkw.com/dksih/QBM/2012/3/22/1570818204868608/1570818210324480/STEM/b18484264a8a4d4b96a55e77f757e548.png)
![](https://img.xkw.com/dksih/QBM/2012/3/22/1570818204868608/1570818210324480/STEM/4e5551f105934d3a9c4ebe6be17ac12d.png)
求
![](https://img.xkw.com/dksih/QBM/2012/3/22/1570818204868608/1570818210324480/STEM/b18484264a8a4d4b96a55e77f757e548.png)
![](https://img.xkw.com/dksih/QBM/2012/3/22/1570818204868608/1570818210324480/STEM/37f0b721192d4235a13bfbfd0f01f5d5.png)
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11-12高三上·河南洛阳·期末
4 . 选修4-1:几何证明选讲
如图,在△ABC中,∠ABC=90°,以BC为直径的圆O交
![](https://img.xkw.com/dksih/QBM/2011/5/19/1570209865703424/1570209870929920/STEM/0ae9fb78725341509c77d9d9f138fd59.png?resizew=89)
AC于点D,设E为AB的中点.
(1)求证:直线DE为圆O的切线;
(2)设CE交圆O于点F,求证:CD·CA=CF·CE.
如图,在△ABC中,∠ABC=90°,以BC为直径的圆O交
![](https://img.xkw.com/dksih/QBM/2011/5/19/1570209865703424/1570209870929920/STEM/0ae9fb78725341509c77d9d9f138fd59.png?resizew=89)
AC于点D,设E为AB的中点.
(1)求证:直线DE为圆O的切线;
(2)设CE交圆O于点F,求证:CD·CA=CF·CE.
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9-10高二下·新疆·阶段练习
5 . 已知:如图,在等腰梯形ABCD中,AD∥BC,AB=DC,过点D作AC的平行线DE,交BA的延长线于点E.求证:
![](https://img.xkw.com/dksih/QBM/2014/4/30/1571696661061632/1571696666591232/STEM/5017d5fc40b341f2be9a7d118199cc2d.png)
(1)△ABC≌△DCB;
(2)DE·DC=AE·BD.
![](https://img.xkw.com/dksih/QBM/2014/4/30/1571696661061632/1571696666591232/STEM/5017d5fc40b341f2be9a7d118199cc2d.png)
(1)△ABC≌△DCB;
(2)DE·DC=AE·BD.
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6 . 选修4-1:几何证明选讲
如图,点
为圆
上一点,
为圆的切线,
为圆的直径,
.
![](https://img.xkw.com/dksih/QBM/2016/10/24/1573091929161728/1573091935461376/STEM/98f63f05550b458a9e48973aa6985d16.png)
(1)若
交圆
于点
,
,求
的长;
(2)若连接
并延长交圆
于
两点,
于
,求
的长.
如图,点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63a253c7fdf589ee3dece13d5b5b5732.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4eedae8d316c76e3d0b451256de03fb9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3fc2678691226b1d08e6d84242692a43.png)
![](https://img.xkw.com/dksih/QBM/2016/10/24/1573091929161728/1573091935461376/STEM/98f63f05550b458a9e48973aa6985d16.png)
(1)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fc5adb5eb60ae4435a12d93854066298.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e312a36dd76bbadbd8dd00fa8a6fb312.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4eedae8d316c76e3d0b451256de03fb9.png)
(2)若连接
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/abd13974aebe38eb2a1d744a01ea5aa5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/01c74a907dda6bb7d9d56d009d9df253.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c39fb8a04fd5261ad1875bab73f047c1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
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