如图,矩形纸片ABCD中,AB=16,将纸片折叠,使顶点B落在边AD上的E点处,BG=20.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/1/19/b0eb15d2-6aa4-43a9-9786-bea9264e7621.png?resizew=428)
(1)当折痕的另一端F在AB边上时,如图.求
的面积;
(2)当折痕的另一端F在AD边上时,如图.证明四边形BGEF为菱形,并求出折痕GF的长.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/1/19/b0eb15d2-6aa4-43a9-9786-bea9264e7621.png?resizew=428)
(1)当折痕的另一端F在AB边上时,如图.求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/36e5e61804ce550636a0354e0a78a22d.png)
(2)当折痕的另一端F在AD边上时,如图.证明四边形BGEF为菱形,并求出折痕GF的长.
更新时间:2020-07-15 23:07:50
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【推荐1】综合与实践课上,老师让同学们以“矩形的折叠”为主题开展数学活动.
(1)操作判断:操作一:对折矩形纸片
,使
与
重合,得到折痕
,把纸片展平;
操作二:在
上选一点P,(点P不与点A,D重合)沿
折叠,使点A落在矩形内部点M处,把纸片展平,连接
,
;
根据以上操作,①如图1,当点M在
上时,
______度,
______度.
②如图2,当点M限制在长方形纸片内(长方形纸片较长的一边足够长),设
,
,则
,
的数量关系是______;当
时,
______度.
(2)迁移探究:小华将矩形纸片换成正方形纸片,继续探究,过程如下:将正方形纸片
按照(1)中的方式操作,并延
交
于点
,连接
.如图3,判断
与
的数量关系,并说明理由.
(3)拓展应用:在(2)的探究中,已知正方形纸片
的边长为4,当
时,直接写出
的长.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/8/9/50215b39-a2e4-41fb-ad7c-e3ceacae32b0.png?resizew=161)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/8/9/2b310089-2271-4453-a8cd-f9f67460fb15.png?resizew=142)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/8/9/a914d2b7-5f9b-48b3-99f3-339b7583fd15.png?resizew=133)
(1)操作判断:操作一:对折矩形纸片
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/49b50357a6545cae8348e3059312f520.png)
操作二:在
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2cdba1337ec85fa9722cb4b320a82ae6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/892909e49156f7dcc0650fcd65243877.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e69d2b798744645af88a4fa411344a83.png)
根据以上操作,①如图1,当点M在
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/49b50357a6545cae8348e3059312f520.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5961764f4c33ea249a94a3a03818549d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1ba2b6218ab865c56f673b2196460694.png)
②如图2,当点M限制在长方形纸片内(长方形纸片较长的一边足够长),设
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b8573bdd09f4da66c67306ae060801a8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f6bb999aca8148924733d76cc039273f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e170f206fdbbd834aad7580c727e2cc6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5b5858ee1ce52b251816757257a11c29.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ee6adf0d2b01463f8e583eb4cf6754cf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5961764f4c33ea249a94a3a03818549d.png)
(2)迁移探究:小华将矩形纸片换成正方形纸片,继续探究,过程如下:将正方形纸片
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/892909e49156f7dcc0650fcd65243877.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/acc290b44635265137fdf13146b6a6d9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cb6ede9761b5b90f8dc137708e1ee90f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/95cd4848ce65d25d3bb30a725322ca8f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/33149bfd164e70c6743fa0c97e9a897f.png)
(3)拓展应用:在(2)的探究中,已知正方形纸片
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bc5c276923c1a46eaf18193604fdb6b0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/20a541b81584a032f571159ea152c85a.png)
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【推荐2】如图,在△ABC中,∠C=90°,把△ABC沿直线DE折叠,使△ADE与△BDE重合.
![](https://img.xkw.com/dksih/QBM/editorImg/2024/4/8/04cbc44c-1812-4de1-86b8-3b0144c1f54b.png?resizew=200)
(1)若∠A=35°,则∠CBD的度数为________;
(2)若AC=8,BC=6,求AD的长;
(3)当AB=m(m>0),△ABC的面积为m+1时,求△BCD的周长.(用含m的代数式表示)
![](https://img.xkw.com/dksih/QBM/editorImg/2024/4/8/04cbc44c-1812-4de1-86b8-3b0144c1f54b.png?resizew=200)
(1)若∠A=35°,则∠CBD的度数为________;
(2)若AC=8,BC=6,求AD的长;
(3)当AB=m(m>0),△ABC的面积为m+1时,求△BCD的周长.(用含m的代数式表示)
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【推荐1】如图1,平面直角坐标系
中,
,反比例函数
的图象分别交矩形
的两边
、
于E、F(E、F不与A重合),沿着
将矩形
折叠使A、D重合
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/1/607b1032-61c6-4633-8fe0-ee35fe932886.png?resizew=674)
(1)如图2,连接
,求证:
;
(2)当点D落在矩形
内部时,求k的取值范围;
(3)如图3,连接
,求
的最小值,并直接写出此时点D的坐标.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7ee31829d0d4d5f779a957d7df8058ab.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e1b4315630139326aff4ffc04c765d10.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5ff4dc731bb311e88109839f15e69478.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/49b50357a6545cae8348e3059312f520.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/99ca6d348c4c0f53eb995246e1cb5ae7.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/1/607b1032-61c6-4633-8fe0-ee35fe932886.png?resizew=674)
(1)如图2,连接
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ee73452ee4d5437f1399f1235b95e55f.png)
(2)当点D落在矩形
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/99ca6d348c4c0f53eb995246e1cb5ae7.png)
(3)如图3,连接
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
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【推荐2】如图,已知矩形纸片ABCD的长
,宽
,点E,F分别是边BC,AD上的点,
.把矩形纸片沿着直线EF翻折,点A,B的对应点分别为
,
.直线
交射线AD于点G.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/9/24/dece1b96-6d02-46fa-8edc-5ade2b744c7a.png?resizew=186)
(1)若
交AD于点P,求证:
,
;
(2)若
交AD于点P,求证:四边形CEFG是平行四边形;
(3)若四边形CEFG为菱形,求它的对角线长的比值
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/07140f277a35733d8c97577ccdd4e3ab.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d2c15801fee2405573677484f5dcfa4.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6eb97aff0960e2640314888a38e7169c.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/9/24/dece1b96-6d02-46fa-8edc-5ade2b744c7a.png?resizew=186)
(1)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3f3a9293c39b2595efa1347c541daa95.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4b30155e0e3cf7c5146d3311e5b8da93.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d64b11a4cbd7515a91ebc7404b7dd4fc.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3f3a9293c39b2595efa1347c541daa95.png)
(3)若四边形CEFG为菱形,求它的对角线长的比值
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6184f18f0603e4cd5da8c39dcb0b2c0c.png)
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【推荐1】问题背景:
△ABC和△CDE均为等边三角形,且边长分别为a,b,点D,E分别在边AC,BC上,点F,G,H,I分别为AB,BE,ED,AD的中点,连接FG,GH,HI,IF
猜想证明:
![](https://img.xkw.com/dksih/QBM/editorImg/2022/10/2/d6964d13-e887-4e1e-8733-6c381c553d3e.png?resizew=429)
(1)如图①,判断四边形FGHI是什么特殊四边形,并说明理由.
(2)当a=6,b=2时,求四边形FGHI的周长.
拓展延伸:
(3)如图②,当四边形FGHI是正方形时,连接AE,BD相交于点N,点N,H恰好在FC上.求证:△ABN和△DEN均为等腰直角三角形.
△ABC和△CDE均为等边三角形,且边长分别为a,b,点D,E分别在边AC,BC上,点F,G,H,I分别为AB,BE,ED,AD的中点,连接FG,GH,HI,IF
猜想证明:
![](https://img.xkw.com/dksih/QBM/editorImg/2022/10/2/d6964d13-e887-4e1e-8733-6c381c553d3e.png?resizew=429)
(1)如图①,判断四边形FGHI是什么特殊四边形,并说明理由.
(2)当a=6,b=2时,求四边形FGHI的周长.
拓展延伸:
(3)如图②,当四边形FGHI是正方形时,连接AE,BD相交于点N,点N,H恰好在FC上.求证:△ABN和△DEN均为等腰直角三角形.
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【推荐2】如图,在平面直角坐标系xOy中,正方形OABC的顶点A,C分别在x轴,y轴的正半轴上,B(2,2),点D在CB边上,E是AB的中点,连接OD,DE,并延长DE交x轴于点P,设CD=m.
![](https://img.xkw.com/dksih/QBM/2022/4/25/2965953349885952/2970776814485504/STEM/fa18fe0e825e4b338eefd51bed978a1c.png?resizew=157)
(1)求点P的坐标(用含m的式子表示);
(2)当OD=PD时,求m的值;
(3)在第(2)题的条件下,作EF∥x轴交OD于点F,连接CF,
①求证:四边形CDEF是平行四边形;
②四边形CDEF能否为菱形?请说明理由.
![](https://img.xkw.com/dksih/QBM/2022/4/25/2965953349885952/2970776814485504/STEM/fa18fe0e825e4b338eefd51bed978a1c.png?resizew=157)
(1)求点P的坐标(用含m的式子表示);
(2)当OD=PD时,求m的值;
(3)在第(2)题的条件下,作EF∥x轴交OD于点F,连接CF,
①求证:四边形CDEF是平行四边形;
②四边形CDEF能否为菱形?请说明理由.
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【推荐3】如图,在ABC 中, AD 是 BC 边上的中线,点 E 是 AD 的中点,过点 A 作AF // BC 交 BE 的延长线于 F ,连接CF .
(1)求证: AEF DEB ;
(2)若BAC 90,试判断四边形 ADCF 的形状,并证明你的结论;
(3)在(2)的情况下,如果 AC 2 ,点 M 在 AC 线段上移动,当 MB MD 有最小值时,求 AM 的长度(提示:以 D 点为原点, AD 为 y 正半轴, DC 为 x 正轴建立平面直角坐标系).
(1)求证: AEF DEB ;
(2)若BAC 90,试判断四边形 ADCF 的形状,并证明你的结论;
(3)在(2)的情况下,如果 AC 2 ,点 M 在 AC 线段上移动,当 MB MD 有最小值时,求 AM 的长度(提示:以 D 点为原点, AD 为 y 正半轴, DC 为 x 正轴建立平面直角坐标系).
![](https://img.xkw.com/dksih/QBM/2019/7/30/2258179396280320/2288408345649152/STEM/d5b561cea29341dabd4fcae48f928d52.png?resizew=218)
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