如图所示,⊙O的直径AB和弦CD交于E,已知AE=6cm,EB=2cm,∠CEA=30°,求CD的长.
![](https://img.xkw.com/dksih/QBM/2021/11/27/2860155331911680/2864538900357120/STEM/73cabaff-fd9c-49a2-a2c1-417c5f22b39f.png?resizew=169)
20-21九年级上·北京·单元测试 查看更多[2]
更新时间:2021-12-03 13:42:13
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相似题推荐
解答题-问答题
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适中
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【推荐1】如图,在平面直角坐标系中,
为原点,等边
的顶点
,
在
轴上,顶点
的坐标为
,
的平分线交
轴于点
.
(1)如图①,求点
坐标;
(2)如图②,
为
轴上一点,以
为边,在第一象限内作等边
,连接
并延长交
轴于点
.求
的长;
(3)如图③,在(1)的条件下,
为
轴正半轴上
点上方的任意一点,在
右上方作
交
延长线于
点,求证:
是定值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/78d7d89dc359a3cdd60144757dad63df.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7cbce11aa19b8bd2bf6ee5a834e005de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d053b14c8588eee2acbbe44fc37a6886.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2024/1/17/35b44238-c98e-44b1-af7c-c600b5965598.png?resizew=339)
(1)如图①,求点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
(2)如图②,
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4eedae8d316c76e3d0b451256de03fb9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5ff39c7aa648afd1080206c8080ff79e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2319a01218514917e446dfc807a625ff.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d053b14c8588eee2acbbe44fc37a6886.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/895dc3dc3a6606ff487a4c4863e18509.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/307bd991211ec79b47a4be52933bb8e7.png)
(3)如图③,在(1)的条件下,
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d053b14c8588eee2acbbe44fc37a6886.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e69d2b798744645af88a4fa411344a83.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/578dfa8a3cb95a50f1349ac9c59d2050.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/54a5d7d3b6b63fe5c24c3907b7a8eaa3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d5b109da727d30a4af0d6069099d8e32.png)
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解题方法
【推荐2】综合与实践
完成任务:
(1)填空:上述材料中的依据是________(填“
”或“
”或“
”或“
”)
【发现问题】
同学们通过交流后发现,已知
可证得
,已知
同样可证得
,为了验证这个结论是否具有一般性,又进行了如下探究.
【迁移探究】
(2)在正方形
中,点E在
上,点M,N分别在
上,连接
交于点P.甲小组同学根据
画出图形如图2所示,乙小组同学根据
画出图形如图3所示.甲小组同学发现已知
仍能证明
,乙小组同学发现已知
无法证明
一定成立.
,求证:
;
②在图3中,若
,则
的度数为多少?
【拓展应用】
(3)如图4,在正方形
中,
,点E在边
上,点M在边
上,且
,点F,N分别在直线
上,若
,当直线
与直线
所夹较小角的度数为
时,请直接写出
的长.
数学课上,老师提出了这样一个问题:如图1,在正方形![]() ![]() ![]()
由同角的余角相等可得 ![]() ![]() ![]() ![]() ![]() 乙小组的同学猜想,其他条件不变,若已知 ![]() ![]() 由 ![]() ![]() ![]() ![]() ![]() |
(1)填空:上述材料中的依据是________(填“
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5a290f047f50481318d040c604d72f7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9beb8b968744573e593ac28451c69729.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4351a730f61bb998bab8f0b7848912d7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d5eb2decaa6be2df36a5e4b7fabf585d.png)
【发现问题】
同学们通过交流后发现,已知
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a4e22ba3e6e1c1d6b12d9b8baa8d1f02.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/04f8eebda19eded2b059774a8c2666c3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/04f8eebda19eded2b059774a8c2666c3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a4e22ba3e6e1c1d6b12d9b8baa8d1f02.png)
【迁移探究】
(2)在正方形
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6d93949d8a15aca4e79cedb978590571.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a96f8239510ab14f8c084b5e78b5b8bb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/13c4a875c62b36bcc95d629b780d8ed4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bc77bde58cab23c53d53733c505115f9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/13c4a875c62b36bcc95d629b780d8ed4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bc77bde58cab23c53d53733c505115f9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bc77bde58cab23c53d53733c505115f9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/13c4a875c62b36bcc95d629b780d8ed4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/13c4a875c62b36bcc95d629b780d8ed4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bc77bde58cab23c53d53733c505115f9.png)
②在图3中,若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b2a9ab5a9114daaa0fd3f6c5f1885f90.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6b14ee179b2f15c7c7ba0a82cdd67234.png)
【拓展应用】
(3)如图4,在正方形
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/efc6e4b936d7a800e839a30c3839574d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bf74dd4bb5a02861f38efcf8f3d5d7b6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6eceff9b68796f5ccd4daa4028e3a182.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5f22a1134cfeea008409510d719041fd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/49b50357a6545cae8348e3059312f520.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411461db15ee8086332c531e086c40c7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f6b86c22b670a8e9f3896f9e8883fbbb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4cae70b8a9d2d2e96dea62c00ced04b9.png)
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【推荐1】已知AC,EC分别是四边形ABCD和EFCG的对角线,直线AE与直线BF交于点H
(1)观查猜想
如图1,当四边形ABCD和EFCG均为正方形时,线段AE和BF的数量关系是 ;∠AHB= .
(2)探究证明
如图2,当四边形ABCD和FFCG均为矩形,且∠ACB=∠ECF=30°时,(1)中的结论是否仍然成立,并说明理由.
(3)拓展延伸
在(2)的条件下,若BC=9,FC=6,将矩形EFCG绕点C旋转,在整个旋转过程中,当A、E、F三点共线时,请直接写出点B到直线AE的距离.
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【推荐2】如图,某储藏室入口的截面是一个半径为
的半圆形,一个长宽高分别是
,
,
的箱子能放进储藏室吗?为什么?
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1f328ba89c0a92a4447788b65571f7aa.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e5c71ba69433849c3349a5cc417ee36.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1f328ba89c0a92a4447788b65571f7aa.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/17b514ca29d7d7df3ccc349e7e93e5fc.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/10/21/90e9b0cc-883c-4186-9f5f-4f4210a5c265.png?resizew=115)
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【推荐1】在
中,
,
,过点B作
,垂足为点D.
(1)求
的值;
(2)点E是
延长线上一点,连接
,当
时,求线段
的长.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5c8817091d0f4b7d7ac6df560cb63c68.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/07160f14b3b453bebb64cb2bf96dc85a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/70734a8e672376bb0bd1522e229f86a2.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/8/13/b15a0e39-4845-4022-b6ac-ccb325e392d8.png?resizew=139)
(1)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0617c9004b48a6f8d0793d0acead3870.png)
(2)点E是
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d40b319212a7e7528b053e1c7097e966.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4eedae8d316c76e3d0b451256de03fb9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/571ffae2f77df57a8e121fdb1ec02bb5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4eedae8d316c76e3d0b451256de03fb9.png)
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【推荐2】如图,在
中,对角线
与
相交于点
,过点
作
交
延长线于点
.
![](https://img.xkw.com/dksih/QBM/editorImg/2024/1/25/5ee41ee9-95fe-4202-9e51-0b2286b0c091.png?resizew=132)
(1)求证:
;
(2)若
,求
的长.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5138a9f70d5e8b0580e30fef6eb7baef.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d40b319212a7e7528b053e1c7097e966.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7599f34b3ba3122bd3c2f2517029bbc2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f913298f0fae9f55377a8deab9f099dd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2024/1/25/5ee41ee9-95fe-4202-9e51-0b2286b0c091.png?resizew=132)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cfc1f76257275ab4b04f9bc913535670.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6b766ac4c308be08d4103136de68092a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4eedae8d316c76e3d0b451256de03fb9.png)
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【推荐1】如图,在
中,直径
与弦
的延长线相交于点
,
,
,弦
于点
,连接
.
(1)求
的度数.
(2)若
,求
的长.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d9ccea461315a9d05aa0193b937d4bfe.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b79dd200766db27fb90d6bd1992cf658.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e1ffb98f1e3c1317c0db403d3af04bdc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/aaae9fb569733d13e919aadcfbc07d30.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/71b6b3dc298db8c3ed2ae3c365847731.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/07b1a11cfc34144d6236a48b00dbb5af.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/73465a1f9aa03481295bf6bd3c6903ac.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b1a3eb9576531c4ca1077be7cb5ef14b.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/11/19/f88f0099-0fe6-42a7-befc-44bb46d46fe3.png?resizew=190)
(1)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ec732664c82259ab1e93c1509777bd32.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/52423e252340d1fb40096c726db184e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e8120f2eeb724c756b5f84a14c6df527.png)
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适中
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【推荐2】在等边
中,D是边
上一动点,连接
,将
绕点D顺时针旋转
得到
,连接
.
![](https://img.xkw.com/dksih/QBM/editorImg/2024/1/17/4fd7c7a5-2996-4603-ba34-f43927bfe170.png?resizew=468)
(1)如图1,当B、A、E三点共线时,连接
,若
,求
的长;
(2)如图2,取
中点F,连接
,猜想
与
存在的数量关系,并证明你的猜想;
(3)如图3,在(2)的条件下,连接
交于G点.若
,请直接写出
值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d40b319212a7e7528b053e1c7097e966.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d40b319212a7e7528b053e1c7097e966.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a6c0927afc571a7c966c98192040979e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e6e490f703eb6c9bb1278c78ebc2d661.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4eedae8d316c76e3d0b451256de03fb9.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2024/1/17/4fd7c7a5-2996-4603-ba34-f43927bfe170.png?resizew=468)
(1)如图1,当B、A、E三点共线时,连接
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/68a83fdd2ba72a2dba0b6b10bb3e06b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fcd0ced286a0fbc7e4862f8147264277.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/68a83fdd2ba72a2dba0b6b10bb3e06b9.png)
(2)如图2,取
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4eedae8d316c76e3d0b451256de03fb9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d004d2d115b477ade6af7ddb93db0df8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d004d2d115b477ade6af7ddb93db0df8.png)
(3)如图3,在(2)的条件下,连接
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b67a5e7cbd36c9b1a103b5e48666f801.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/41d72501af35b1b3003bf0ed308424dd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/01c1e48bbdf38aa49e8722ea3824d803.png)
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