如图,矩形
中,
,将此矩形绕点B顺时针方向旋转θ(
)得到矩形
,点
在边
上.
(1)若
,求在旋转过程中,点D到点
所经过路径的长度;
(2)将矩形
继续绕点B顺时针方向旋转得到矩形
,点
在
的延长线上,设边
与
交于点E,若
,求
的值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/217697df3d2e2f9999b98885d5d7bbc7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4e552716f71ddda6b1566fcb7eb11f52.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e963c942be5c658864dee9bb352b36c8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a18722354086c42e62334983fc50eb6a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
(1)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0f707a82c433430523ce6d792b11aad9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6795cae2df43a722e1355e9562d93c09.png)
(2)将矩形
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e963c942be5c658864dee9bb352b36c8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1e246f002255e27bd30c578381fd4cf2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c296e45b84cf67a98939aa7334e7d478.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/668438e15423368cd744445e824d18a1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f1e1029a6b6b16124f201fa80e42d01a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/44ab7024f73ff0cb7e6a48197538a91e.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/10/6/342e2bc4-a8d7-4cd3-b526-279d247a2af7.png?resizew=249)
2018·江苏无锡·中考真题 查看更多[5]
江苏省无锡市2018年中考数学试题(已下线)2018年中考试题分项版解析汇编【第二期】专题5.1 图形的平移对称与旋转江苏省镇江市丹徒区江心实验学校2019-2020学年九年级下学期4月月考数学试题(已下线)专题24.33 弧长及扇形的面积(培优篇)(专项练习)-2022-2023学年九年级数学上册基础知识专项讲练(人教版)(已下线)专题3.36 弧长及扇形的面积(培优篇)(专项练习)-2022-2023学年九年级数学下册基础知识专项讲练(北师大版)
更新时间:2018-07-09 22:41:33
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解答题-证明题
|
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(0.4)
【推荐1】如图1,菱形
中,
,
.点
为射线
上一动点,在射线
上取一点
,连接
,
,使
.作
的外接圆,设圆心为
.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/12/13/f1b23f70-78c2-490c-8dcb-dd4ecd45ce9c.png?resizew=393)
(1)当圆心
在
上时,
___________;
(2)当点
在边
上时,
①判断
与
的位置关系,并证明;
②当
为何值时,
有最大值?并求出最大值;
(3)如图2,连接
,若
,则
;将优弧
沿
翻折交射线
于点
,则
的弧长
___________.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5cb3f9a5da641be35117fd35ba07a6aa.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1d05cf9c349a95b54fff7dffb062d31d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/76d527d4795ece4a5756d1cf8dba31e1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b79dd200766db27fb90d6bd1992cf658.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f96461af9193d5d7867ddf8fcbefcaec.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d48943db264c08adaf6ae0766fd56459.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/af6cd332590b9eb4032b51a39134d219.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c13c26de563c1971c607d233bae097e7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/283b6c8adb38ca36a40857d7d0f1d1f9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/12/13/f1b23f70-78c2-490c-8dcb-dd4ecd45ce9c.png?resizew=393)
(1)当圆心
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b79dd200766db27fb90d6bd1992cf658.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/101f8785e19f1b7e8f68ade2d1ccbcb2.png)
(2)当点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/88929f4ba0851730d5f941d426b87548.png)
①判断
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d9ccea461315a9d05aa0193b937d4bfe.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d48943db264c08adaf6ae0766fd56459.png)
②当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/80672dda9430cb42b3136bcb1b67bbad.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b9f79d7939c88e9702962e5917cad290.png)
(3)如图2,连接
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e1a9c6a736e6eac98a676fa3232db5a5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/09d0157310b49104bd2f604b4f83ecd2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/789eba2a0dde4bbd34a963ea7b136cd9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1a3137705cb4170baafa66ff46eefb7a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1a3137705cb4170baafa66ff46eefb7a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e1a9c6a736e6eac98a676fa3232db5a5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/acc290b44635265137fdf13146b6a6d9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e430f13f42cf2d44aa0f0e20b959684f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6706fe00b4e231e62d9ecbec567d526b.png)
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【推荐2】筒车是我国古代利用水利驱动的灌溉工具,如图所示 2,筒车
按逆时针方向转动,每绕一圈需要
,筒车与水面分别交于
、
,且.
,筒车的轴心
距离水面的高度
长为
,筒车上均匀分布着若干个盛水筒,若以某个盛水筒
刚浮出水面时开始计算时间.
的半径;
(2)盛水桶
从刚浮出水面绕到离水面最高点时,求它走过的路径长:
(3)拟修建接水槽
,盛水桶绕至接水槽后自然翻落,水沿着接水槽流入农田.
所在直线与
相切,当盛水桶
从浮出水面至绕到
上用时
时,求接水槽
的长.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d97cdc586744d208b6f69c9813af977.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/72a07d7da7881567ffdfea93aa4d6cab.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/5859f40b1a1a55474e52e4986b03a570.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/72a43d26595bd2c7615138107a672e6a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f71a41641aa0d0e45a3c03d3d2c1196b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d97cdc586744d208b6f69c9813af977.png)
(2)盛水桶
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
(3)拟修建接水槽
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411461db15ee8086332c531e086c40c7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411461db15ee8086332c531e086c40c7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d97cdc586744d208b6f69c9813af977.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411461db15ee8086332c531e086c40c7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/68b87f4e19e910f0db23cfb9d4f693b4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411461db15ee8086332c531e086c40c7.png)
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真题
名校
【推荐1】如图,
是
的直径,
,
的弦
于点
,
.过点
作
的切线交
的延长线于点
,连接
.
平分
;
(2)
为
上一点,连接
交
于点
,若
,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/80b1107f50f4fc687e2cc5a11fb4486e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d97cdc586744d208b6f69c9813af977.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8b757f0c42ae5c9a2d6a4b19e5877b27.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/eca7e1a727ba332984ad857b3d25344d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d97cdc586744d208b6f69c9813af977.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/300d3ec6447250bb25915ae86873929a.png)
(2)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/895dc3dc3a6606ff487a4c4863e18509.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f6f9353ca110c8b81561455b232dbc15.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/abf80148409afb32ced0b4f59f1ba709.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/73465a1f9aa03481295bf6bd3c6903ac.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2bd4065ad4ca073423581aaa68f69376.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bcdae78f4d3b8d8213ac3ac9a9567eb5.png)
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真题
【推荐2】综合运用
如图1,在平面直角坐标系中,正方形
的顶点A在
轴的正半轴上,如图2,将正方形
绕点
逆时针旋转,旋转角为
,
交直线
于点
,
交
轴于点
.
(1)当旋转角
为多少度时,
;(直接写出结果,不要求写解答过程)
(2)若点
,求
的长;
(3)如图3,对角线
交
轴于点
,交直线
于点
,连接
,将
与
的面积分别记为
与
,设
,
,求
关于
的函数表达式.
如图1,在平面直角坐标系中,正方形
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3241d7fedd89d85711acd7a2635298af.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3241d7fedd89d85711acd7a2635298af.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/447bdb83bb93996f9acb0c2abc4b6b10.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d77f5191798242b7b9b88a75e17e4425.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d053b14c8588eee2acbbe44fc37a6886.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/7/1/f96cacd5-dee8-47c6-9456-a06098d23ba9.png?resizew=471)
(1)当旋转角
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83b723421b10b3735be77e1c79fa1425.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dcf2e3236ea30ee2c37928b98041f13a.png)
(2)若点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/753f70f89ee9f98bbb12c866087d1be1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/735056c174e8dd7906257a2a50a962a7.png)
(3)如图3,对角线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d053b14c8588eee2acbbe44fc37a6886.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d77f5191798242b7b9b88a75e17e4425.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/54a5d7d3b6b63fe5c24c3907b7a8eaa3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1460aa3d83df61f6c411b34412135451.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5b6e0df8ad8998b75cabd2ad7eeaefd7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/20bb77c849e0ce2a7d06ff0ca900fb28.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e097c8d4c948de063796bd19f85b3a9a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1e0bd63f55069a3bc870915010b39225.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e450316d80c6525899fd8e41d7116ef5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dc268d27f636e3417a64ad34c96a1a2b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cf231f8f86fb922df4ca0c87f044cec3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
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【推荐3】如图(1),在平面直角坐标系中,矩形ABCO,B点坐标为(4,3),抛物线y=
x2+bx+c经过矩形ABCO的顶点B、C,D为BC的中点,直线AD与y轴交于E点,与抛物线y=
x2+bx+c交于第四象限的F点.
![](https://img.xkw.com/dksih/QBM/2013/5/30/1578224534274048/1578224534880256/STEM/caec5943f148475cbc6ce51d08e94376.png)
(1)求该抛物线解析式与F点坐标;
(2)如图,动点P从点C出发,沿线段CB以每秒1个单位长度的速度向终点B运动;
同时,动点M从点A出发,沿线段AE以每秒
个单位长度的速度向终点E运动.过
点P作PH⊥OA,垂足为H,连接MP,MH.设点P的运动时间为t秒.
①问EP+PH+HF是否有最小值,如果有,求出t的值;如果没有,请说明理由.
②若△PMH是等腰三角形,求出此时t的值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5f94407f032de7a4c49ec6dc8809133c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5f94407f032de7a4c49ec6dc8809133c.png)
![](https://img.xkw.com/dksih/QBM/2013/5/30/1578224534274048/1578224534880256/STEM/caec5943f148475cbc6ce51d08e94376.png)
(1)求该抛物线解析式与F点坐标;
(2)如图,动点P从点C出发,沿线段CB以每秒1个单位长度的速度向终点B运动;
同时,动点M从点A出发,沿线段AE以每秒
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/700762875cb4f15b556a72f10a42ac9f.png)
点P作PH⊥OA,垂足为H,连接MP,MH.设点P的运动时间为t秒.
①问EP+PH+HF是否有最小值,如果有,求出t的值;如果没有,请说明理由.
②若△PMH是等腰三角形,求出此时t的值.
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解题方法
【推荐1】已知:如图,在Rt△ABC中,∠ACB=90°,BC=3,AC=4.D是边AB的中点,点E为边AC上的一个动点(与点A、C不重合),过点E作EF∥AB,交边BC于点F.联结DE、DF,设CE=x.
![](https://img.xkw.com/dksih/QBM/2020/6/25/2492418718605312/2493737355149312/STEM/803767745bec40d58f36fd396dc4d1a8.png?resizew=482)
(1)当x =1时,求△DEF的面积;
(2)如果点D关于EF的对称点为D’,点D’ 恰好落在边AC上时,求x的值;
(3)以点A为圆心,AE长为半径的圆与以点F为圆心,EF长为半径的圆相交,另一个交点H恰好落在线段DE上,求x的值.
![](https://img.xkw.com/dksih/QBM/2020/6/25/2492418718605312/2493737355149312/STEM/803767745bec40d58f36fd396dc4d1a8.png?resizew=482)
(1)当x =1时,求△DEF的面积;
(2)如果点D关于EF的对称点为D’,点D’ 恰好落在边AC上时,求x的值;
(3)以点A为圆心,AE长为半径的圆与以点F为圆心,EF长为半径的圆相交,另一个交点H恰好落在线段DE上,求x的值.
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【推荐2】如图,在平面直角坐标系中,矩形
的顶点B的坐标为
,
,
分别落在x轴和y轴上,将
绕点O逆时针旋转,使点B落在y轴上,得到
,
与
相交于点F,反比例函数
的图象经过点F,交
于点G.
![](https://img.xkw.com/dksih/QBM/2023/5/31/3249417632759808/3250323147464704/STEM/9d96aeb44d5b4e958f956019f9189407.png?resizew=240)
(1)求k的值;
(2)若点P在坐标轴上运动,求动点P的坐标,使
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3241d7fedd89d85711acd7a2635298af.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dee05fdbfca9281f1eb74e11c8144938.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ef4113c492885ba7c47fe42ac792578f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/828628c0876b45381c9a0edeb0fec236.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3fe95f656b98b53f71a9d72bf0c9a4b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/32e00bf73d03dded1cf5f83cc5339361.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/683c590673eece14fea3319c4fd5eb55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6b1bd1adfe4cc6566218f19970c2fd3b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9212e728b36c078188606c9d429389d6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://img.xkw.com/dksih/QBM/2023/5/31/3249417632759808/3250323147464704/STEM/9d96aeb44d5b4e958f956019f9189407.png?resizew=240)
(1)求k的值;
(2)若点P在坐标轴上运动,求动点P的坐标,使
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/77db852c74779e66a40bc8475f241b22.png)
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名校
【推荐1】如图,在
中,
,
,D为
的中点,点E为平面内一点,连接
,将
经点D顺时针旋转
,点E的对应点为F,连接
,
,
.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/11/24/04eb617e-1a3a-42ec-95d3-27178ea5fde2.png?resizew=379)
(1)如图1,当点E在边
上时,请直接写出线段
,
之间的数量关系______,位置关系______;
(2)如图2,当点E在
内部时,判断(1)中结论是否依然成立,并说明理由;
(3)
,
,若A,E,F三点共线,请直接写出线段
的值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9c06154cae3bf7a8ce5a1e97a7380875.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/047dc9795efa99b6fb9fdf9778085dab.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e6e490f703eb6c9bb1278c78ebc2d661.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e6e490f703eb6c9bb1278c78ebc2d661.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c02b54dc6b3e1bb6544f47d4c8743fcf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/49b50357a6545cae8348e3059312f520.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/68a83fdd2ba72a2dba0b6b10bb3e06b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4cae70b8a9d2d2e96dea62c00ced04b9.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/11/24/04eb617e-1a3a-42ec-95d3-27178ea5fde2.png?resizew=379)
(1)如图1,当点E在边
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/68a83fdd2ba72a2dba0b6b10bb3e06b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4cae70b8a9d2d2e96dea62c00ced04b9.png)
(2)如图2,当点E在
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
(3)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/edc5df62e8ac9c74a46462519b95479a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6370d6c626bdabf1fc694501ee6c714f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/85c4bdfb0db1e31e8459df1d15f9ab55.png)
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【推荐2】如图,在正方形ABCD中,点E在对角线BD上,EF∥AB交AD于点F,连接BF.
![](https://img.xkw.com/dksih/QBM/2019/4/18/2184953318555648/2185859236732928/STEM/ab82f59af05c49148e0c0829e24fe2e8.png?resizew=418)
(1)如图1,若AB=4,DE=
,求BF的长;
(2)如图2.连接AE,交BF于点H,若DF=HF=2,求线段AB的长;
(3)如图3,连接BF,AB=3
,设EF=x,△BEF的面积为S,请用x的表达式表示S,并求出S的最大值;当S取得最大值时,连接CE,线段DB绕点D顺时针旋转30°得到线段DJ,DJ与CE交于点K,连接CJ,求证:CJ⊥CE.
![](https://img.xkw.com/dksih/QBM/2019/4/18/2184953318555648/2185859236732928/STEM/ab82f59af05c49148e0c0829e24fe2e8.png?resizew=418)
(1)如图1,若AB=4,DE=
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cf298f00799cbf34b4db26f5f63af92f.png)
(2)如图2.连接AE,交BF于点H,若DF=HF=2,求线段AB的长;
(3)如图3,连接BF,AB=3
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cf298f00799cbf34b4db26f5f63af92f.png)
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【推荐3】综合实践
问题背景:借助三角形的中位线可构造一组相似三角形,若将它们绕公共顶点旋转,对应顶点连线的长度存在特殊的数量关系,数学小组对此进行了研究.如图1,在“
中,
,
,分别取
,
的中点D,E,作
.如图2所示,将
绕点A逆时针旋转,连接
,
.
和
的长度存在怎样的数量关系?写出你的猜想,并证明.
(2)性质应用:如图3,当
所在直线首次经过点B时,求
的长.
(3)延伸思考:如图4,在
中,
,
,
,分别取
,
的中点D,E.作
,将
绕点B逆时针旋转,连接
,
.当边
平分线段
时,求
的值.
问题背景:借助三角形的中位线可构造一组相似三角形,若将它们绕公共顶点旋转,对应顶点连线的长度存在特殊的数量关系,数学小组对此进行了研究.如图1,在“
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60d9142db4dd2ef151bf3d4a63afb61e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b37750daa8ba3b3fe3e9e2092f81c848.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a25c28359f8d8da9eaf4672a6cf8ae4f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a25c28359f8d8da9eaf4672a6cf8ae4f.png)
![](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/d40b319212a7e7528b053e1c7097e966.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4eedae8d316c76e3d0b451256de03fb9.png)
(2)性质应用:如图3,当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e6e490f703eb6c9bb1278c78ebc2d661.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4eedae8d316c76e3d0b451256de03fb9.png)
(3)延伸思考:如图4,在
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dd967903ed5a6f640a5b801ec8be0070.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/45acdbac251ca6b76a166c1242e71df9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d2c15801fee2405573677484f5dcfa4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3f8eeeea1c9652cacce976f8129cf520.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/1f2281cb6df0c3c518ce5ed19a02b57e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1f2281cb6df0c3c518ce5ed19a02b57e.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/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e6e490f703eb6c9bb1278c78ebc2d661.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2c7ed9f2339c28aee0b31b3d877e49cc.png)
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