如图,在△ABC中,∠A=30°,AC=BC,以BC为直径的⊙O与边AB交于点D,过D作DE⊥AC于E.
(1)证明:DE为⊙O的切线.
(2)若⊙O的半径为2,求AD的长.
(1)证明:DE为⊙O的切线.
(2)若⊙O的半径为2,求AD的长.
![](https://img.xkw.com/dksih/QBM/2018/10/2/2044825198198784/2045453135511552/STEM/87dfd10a622b4b60901cec6c296156c8.png?resizew=208)
更新时间:2018-10-03 07:47:58
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【推荐1】如图,四边形
中,
,
平分
,
于点
.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/12/29/8713cac3-829b-414d-ba94-9a1e122d3e0b.png?resizew=132)
(1)若
,求证:![](https://staticzujuan.xkw.com/quesimg/Upload/formula/88929f4ba0851730d5f941d426b87548.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a9bfa68259d7a331be323b2038d628a.png)
;
(2)试探究线段
,
,
的数量关系,并说明理由.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5cb3f9a5da641be35117fd35ba07a6aa.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3ec1b79ecee6cb2770b7761acef4ba4a.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2f10681704c4fccfd37664eaf34391dd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f6402a3bb6be38f5bfafacc86c7bd008.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/12/29/8713cac3-829b-414d-ba94-9a1e122d3e0b.png?resizew=132)
(1)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/adb32dae6823f572ffa028d684733c37.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/88929f4ba0851730d5f941d426b87548.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a9bfa68259d7a331be323b2038d628a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/764509115979e9958101808383672ec0.png)
(2)试探究线段
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b79dd200766db27fb90d6bd1992cf658.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d0213c5787a5a6b38d11bceca5567f67.png)
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【推荐2】已知:如图,AB=AC,∠DAE=∠B,求证:△ABE∽△DCA.
![](https://img.xkw.com/dksih/QBM/2019/2/17/2142500008706048/2144162737438720/STEM/f9c43ae4d14a43cca2b76e1652755e77.png?resizew=138)
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【推荐1】如图,在Rt△ABC中,∠ACB=90°,AB=5,BC=3,点D在AB的延长线上,且BD=3,过点D作DE⊥AD,交AC的延长线于点E,以DE为直径的⊙O交AE于点F,交CD于点G.求⊙O的半径并证明G是CD的中点.
![](https://img.xkw.com/dksih/QBM/editorImg/2024/3/9/9f220487-b7c0-4499-8a65-08a7b9bb16be.png?resizew=175)
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【推荐2】如图,在△ABC中,AB=AC,以AC为直径的⊙O交AB于点D,交BC于点E.
(1)求证:BE=CE;
(2)若BD=2,BE=3,求AC的长.
(1)求证:BE=CE;
(2)若BD=2,BE=3,求AC的长.
![](https://img.xkw.com/dksih/QBM/2018/1/4/1852704660504576/1856769983774720/STEM/48146a98ba2849d4bce423d0a343f592.png?resizew=117)
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【推荐1】如图,在Rt△ABC中,∠ABC=90°,AC的垂直平分线分别与AC,BC及AB的延长线相交于点D,E,F,且BF=BC,⊙O是△BEF的外接圆,∠EBF的平分线交EF于点G,交⊙O于点H,连接BD,FH.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/8/23/df7f7a28-0a7a-4110-87f3-036db39beb6b.png?resizew=160)
(1)试判断BD与⊙O的位置关系,并说明理由;
(2)若AB=1,求HG·HB的值.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/8/23/df7f7a28-0a7a-4110-87f3-036db39beb6b.png?resizew=160)
(1)试判断BD与⊙O的位置关系,并说明理由;
(2)若AB=1,求HG·HB的值.
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【推荐2】如图,已知
为
的直径,D是
上的一点,且点C是
的中点,过点C作
直线
于点E.
是
的切线;
(2)连接
,过点O作
于F,延长
交
于M,若B为
的中点,半径为4,求
的长
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d97cdc586744d208b6f69c9813af977.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d97cdc586744d208b6f69c9813af977.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f8b758913f0b039bba68f657380e1f67.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/44b190c8d3d7d7d0e6e959e8a52eae90.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4eedae8d316c76e3d0b451256de03fb9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d97cdc586744d208b6f69c9813af977.png)
(2)连接
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8e99cd1610de98c8332da8c4520aad6e.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d97cdc586744d208b6f69c9813af977.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/469efa85a031f27ead9e05cff02eada2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6cad4595d5352b2884568a59d8d766a4.png)
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解答题-证明题
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【推荐1】如图,点E是
的内心,
的延长线和
的外接圆相交于点D.
;
(2)已知
,
,求该圆的半径的长度;
(3)在(2)的条件下,若
,求
的值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/68a83fdd2ba72a2dba0b6b10bb3e06b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/262a173a7cf68e06b4be175df69e2b74.png)
(2)已知
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ea147ada4f0aefdd3808a6a1133792eb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8f790a4990bf39841323dca805210bc0.png)
(3)在(2)的条件下,若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/169145cfb31e4fc502a3b2f47a644831.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/824571232017566dc5df13a3ca8609c5.png)
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解答题-问答题
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(0.65)
【推荐2】如图,在菱形
中,
,
,在直线
上有一点M,
,
,以
为直径的半圆O与直线
相切于点P,点N为半圆弧
上一动点.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/3/18/067220fc-53bb-45dc-b6a5-d9766268acb2.png?resizew=290)
(1)当点P与点M重合时,H为半圆O上一点,则线段
的最小值为______;
(2)半圆O从点M出发沿
做平移运动,速度为每秒1个单位长度,同时点N从点P开始绕圆心顺时针旋转,速度为每秒
,设运动时间为t秒
,解决下列问题:
①当
时,求此时点O到
的距离及扇形
的面积;
②当半圆O与菱形
有交点时,直接写出运动时间t的取值范围.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/284a563413dc0532138fb2a64db8cc2b.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e42a8ba3ea434605e0574339efc9c38f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7a5f1641947153c80b987320885a2b57.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7a5f1641947153c80b987320885a2b57.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/3/18/067220fc-53bb-45dc-b6a5-d9766268acb2.png?resizew=290)
(1)当点P与点M重合时,H为半圆O上一点,则线段
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a6655e2fa64a32cd12fe0279afd65d73.png)
(2)半圆O从点M出发沿
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8e5c62f22d7afc5627fcb86599faa8e1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/76c12e76fbd84eeec721386bd3b04cc4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/683cf8de94d118b12cdc337d83b30813.png)
①当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8cbeede118c407a800b05757b9a1393e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c7f11db05569a88a3da8d4b635d0ff94.png)
②当半圆O与菱形
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
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