如图,已知Rt△ABC中,∠ACB=90°.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/6/16/2a43ffe0-ed21-47cd-8762-8275775588fd.png?resizew=150)
(1)求作圆C,使它与AB相切于点D,与AC相交于点E;
(要求尺规作图,不写作法,但应保留作图痕迹,并标明字母)
(2)在(1)中所作的图形中,若BC=2,AC=
,求弧DE的长.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/6/16/2a43ffe0-ed21-47cd-8762-8275775588fd.png?resizew=150)
(1)求作圆C,使它与AB相切于点D,与AC相交于点E;
(要求尺规作图,不写作法,但应保留作图痕迹,并标明字母)
(2)在(1)中所作的图形中,若BC=2,AC=
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/38387ba1cadfd3dfc4dea4ca9f613cea.png)
更新时间:2022-06-12 21:33:25
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解答题-作图题
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【推荐1】在几何学习中,我们遇到这样一个题目:“在四边形
中,
.若
平分
,
,求证:
.”结合学过的知识,可以知道:首先过点C分别作出
、
的垂线,将其转化为证明三角形全等,然后结合补角的知识使问题得到解决.请根据上述的思路,完成下面的作图与填空:
![](https://img.xkw.com/dksih/QBM/editorImg/2024/1/14/59084d29-53d2-47d3-afda-c52b793e73e5.png?resizew=180)
(1)尺规作图:用直尺和圆规,过点C分别作出
、
的垂线,垂足分别是点 E、F(只保留作图痕迹);
(2)证明:∵
,
,
∴
,
又∵
平分
,
∴ .
在
和
中,
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8838b7592d59101a4ad4bafeac70f41f.png)
∴![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f986d2a3b0c8c6cad8e1e9dc476fa6bd.png)
∴ .
又 .
∴
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8b9199a3de404cb13ae7710f73db5c8f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2947ca8e0cdbeb4aab80ce9e7b63ba98.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5a16dc02090b6e9263555061f14fbc8c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8bd602a957d7f6d0940f79a1121b78c6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2024/1/14/59084d29-53d2-47d3-afda-c52b793e73e5.png?resizew=180)
(1)尺规作图:用直尺和圆规,过点C分别作出
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
(2)证明:∵
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f913298f0fae9f55377a8deab9f099dd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0b62ce0cbffa4758c7a0e6fb7ca4d24e.png)
∴
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f5d23ca6f74d2103e7354feaea60500c.png)
又∵
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2947ca8e0cdbeb4aab80ce9e7b63ba98.png)
∴ .
在
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c03fc83cfcc5df2372dfc2a27bc14fde.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/86583630830d6d7827b95553d8a7829e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8838b7592d59101a4ad4bafeac70f41f.png)
∴
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f986d2a3b0c8c6cad8e1e9dc476fa6bd.png)
∴ .
又 .
∴
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8bd602a957d7f6d0940f79a1121b78c6.png)
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【推荐2】已知一直角边和斜边,用尺规作直角三角形,已知:如图线段
,
,求作:
,使
,
,
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/071a7e733d466949ac935b4b8ee8d183.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7e3262fc038bbec5e7c8cc47df08bef7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8e781a2489271bfd1597cba1bb6f5887.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4c884a45b56bc34d79273b067c1520b2.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2024/2/17/373f1f54-dca7-45a9-ad18-cbd3226429ad.png?resizew=120)
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【推荐1】如图,△ABC的边AC与
分别交于C、D两点,且CD是
的直径,AB是
的切线,切点为B,
,
,求图中阴影部分的面积.
![](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/3d97cdc586744d208b6f69c9813af977.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0f3018c687427b6257767eda4a8c6612.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/305a88d4e0249bd16d48eda01331d2d4.png)
![](https://img.xkw.com/dksih/QBM/2021/1/21/2641063576805376/2669767539253248/STEM/e4b2c3eed3c940d9a535b9d7a61dc26d.png?resizew=146)
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【推荐2】如图,
是直角三角形,
,以
为直径的
与边
交于点
,过
作
的切线
交
于
,连接
,交
于
.
![](https://img.xkw.com/dksih/QBM/2020/9/29/2560007300816896/2563308259155968/STEM/7a414fd6-6f47-468f-a023-a6f40e63d9b1.png?resizew=243)
(1)求证:
;
(2)若
,
,求线段
的长.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/45acdbac251ca6b76a166c1242e71df9.png)
![](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/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d97cdc586744d208b6f69c9813af977.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e6e490f703eb6c9bb1278c78ebc2d661.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a299d2b999568e80be8005565ba209a4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d97cdc586744d208b6f69c9813af977.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://img.xkw.com/dksih/QBM/2020/9/29/2560007300816896/2563308259155968/STEM/7a414fd6-6f47-468f-a023-a6f40e63d9b1.png?resizew=243)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/888f3f66a185ab290254e17c251d63ff.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/305a88d4e0249bd16d48eda01331d2d4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/71888bb567d33079b39d8428ff76553d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/49b50357a6545cae8348e3059312f520.png)
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【推荐1】如图,点C在以AB为直径的⊙O上,过点B作⊙O的切线,与AC的延长线交于点D.
(1)求证:∠CBD=∠BAC;
(2)若∠CBD=36°,⊙O的半径为5,则
的长度= .
(1)求证:∠CBD=∠BAC;
(2)若∠CBD=36°,⊙O的半径为5,则
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ed41d321f4c0717ac5b443aad942d9a7.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/10/28/c74dbcb6-fe0b-415b-b87a-82dee993e3cc.png?resizew=118)
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【推荐2】求下图中阴影部分的周长和面积.(结果保留
)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/86ebba6ed1add0fe647c0226614b9290.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/9/14/7fd6afbc-b306-4f47-bdc2-789fb71a2a82.png?resizew=106)
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【推荐3】平面内一个正n边形,将平面内 与正n边形的各顶点距离都小于等于边长的所有点组成的图形称为这个正n边形的“伴侣形”.将正 n边形内 与其各顶点距离都大于等于边长的所有点组成的图形称为这个正n边形的“远伴侣形”.
【观察】如图1,边长为1的等边
,分别以A、B、C为圆心,
长为半径画圆弧,则三条弧
,
,
及其内部所组成的图形上的点到各顶点距离都小于等于1,我们把这个图形称为正
的“伴侣形”.
【判断】
(1)______(填“是”或“不是”)所有的正多边形都有“伴侣形”,______(填“是”或“不是”)所有的正多边形都有“远伴侣形”;
【操作】
(2)如图2,边长为1的正方形
,请作出正方形
的“伴侣形”(将此“伴侣形”打上阴影),求此正方形
的“伴侣形”的周长;
【探究】
(3)结合图3分析,若正n边形的边长为1,则当
时,其“远伴侣形”的周长为______,则当
时,“远伴侣形”的周长为______;
【归纳】
(4)边长为1的正n边形(
),其“远伴侣形”的周长为______.
【观察】如图1,边长为1的等边
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b79dd200766db27fb90d6bd1992cf658.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b79dd200766db27fb90d6bd1992cf658.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/764509115979e9958101808383672ec0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e1a9c6a736e6eac98a676fa3232db5a5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
【判断】
(1)______(填“是”或“不是”)所有的正多边形都有“伴侣形”,______(填“是”或“不是”)所有的正多边形都有“远伴侣形”;
【操作】
(2)如图2,边长为1的正方形
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5cb3f9a5da641be35117fd35ba07a6aa.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5cb3f9a5da641be35117fd35ba07a6aa.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5cb3f9a5da641be35117fd35ba07a6aa.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/11/27/c6c51fee-1d5c-4cd3-aaad-5b878a1f3e05.png?resizew=332)
【探究】
(3)结合图3分析,若正n边形的边长为1,则当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/764eff906937f9b1fb58e5abfb2eb8a3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08ec5d76db9bd05547932966c9913dc2.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/11/27/df3b19a7-f07f-4dad-ab4d-334e10ff05fd.png?resizew=367)
【归纳】
(4)边长为1的正n边形(
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fbcd23a8020d731bd512bb8df45ea594.png)
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【推荐1】如图(1)是一天桥的梯步图,为了方便残疾人出行,准备对梯步进行改建降低坡度,绘制了如图(2)的侧面示意图,点
为梯步顶端,点
为梯步底端,
垂直于水平地面
,并测得
,
米.要使改建后的梯步与水平面的夹角
,求梯步底端向外延伸的长度
(精确到0.1米,
,
,
,
).
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6fbc97ba3138ddbc9e76724cac9cd63d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/657921f28d9ebc92f154ac16d3599b3f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/abad496ea3d96a6e9258a2b131236946.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9e52a8f07834cbbbe4224962672fbbb2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/276947a982897cc26169dd35df7efd7e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/af89634981ae478fb00d20d99a2d8e92.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/94f383f9e0b0490ef992b76dc96db58b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/34210a4239101c0adb7e6d5f4ca729d2.png)
![](https://img.xkw.com/dksih/QBM/2022/4/13/2957164907446272/2961577721536512/STEM/a5966bdd-8698-47ca-938c-c796bf62c070.png?resizew=307)
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【推荐2】随着测量技术的发展,测量飞机可以实现精确的空中测量.如图,为测量我国某海岛两端A、B的距离,我国一架测量飞机在距海平面垂直高度为2千米的点C处,测得端点A的俯角为
,然后沿着平行于
的方向飞行
千米到点D,求某海岛两端A、B的距离.(结果精确到
千米,参考数据:
,
,
,
)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f6b86c22b670a8e9f3896f9e8883fbbb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f270ea1de607d82972b7ffe5e44fb6d0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a87796ee30e6c5d5e6b6285b32abe10c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d905c20af98220ac67887497a57d0fde.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7706f5b08b41380f3ecb0b0264e7d339.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/04ccf45e4cd5726241c6fc7666f86cca.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/460317e7c26f95b9b29cfe1a89b796d6.png)
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