综合与实践:数学课上,同学们以“等边三角形折叠”为主题开展数学活动.
(1)操作判断,操作一:将如图(1)所示的等边三角形纸片折叠,使点B和点C重合,得到折痕
,把纸片展开,如图(2);操作二:将如图(1)所示的等边三角形纸片折叠,分别使点B和点C重合,点A和点C重合,点A和点B重合,折叠三次,得到三条折痕
,
,
,三条折痕的相交于点O,把纸片展开,如图(3);若等边三角形的边长为4,根据以上操作,①
;②
;③
,这三种线段和中,线段和最小的是(填序号)________,最小值是 .
(2)迁移研究:小帅同学将等边三角形纸片换成等腰三角形纸片,继续研究,过程如下:将等腰三角形纸片
按照(1)中的操作二进行折叠,折痕交点为点O,把纸片展开,如图(4),若
,
,求点O到点A的距离.
(3)拓展应用:在等腰△ABC中,已知
,
的面积为10,点O到
三个顶点的距离相等,请直接写出点O到点A的距离.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/8/13/49325bd2-5721-4c04-ace4-7241e0b4ec4c.png?resizew=471)
(1)操作判断,操作一:将如图(1)所示的等边三角形纸片折叠,使点B和点C重合,得到折痕
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/85c4bdfb0db1e31e8459df1d15f9ab55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4cae70b8a9d2d2e96dea62c00ced04b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6151fb896230f2579d516af4c67e634a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b57041caba590305ccb37a3a7fbd2a14.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c62635ee088808196e070c44ba6c20fb.png)
(2)迁移研究:小帅同学将等边三角形纸片换成等腰三角形纸片,继续研究,过程如下:将等腰三角形纸片
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6eeb0c8df3d8c5260768c5e407b3583a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b939af5ba06e279cce39396aaf0fae06.png)
(3)拓展应用:在等腰△ABC中,已知
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5c8817091d0f4b7d7ac6df560cb63c68.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
更新时间:2023-08-04 18:31:54
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解答题-问答题
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解题方法
【推荐1】△ABC是等边三角形.(等边三角形三边相等,三个角均为60°)
(1)如图1,若D是边BC上的一动点,连接AD ,以AD为边向右作等边△ADE,连接CE,说明△ABD≌△ACE.
(2)若D是射线BC上的一动点,连接AD ,以AD为边向右作等边△ADE,连接CE,△ABC的边长为5,若CD=1,求CE.
(3)若D是射线BC上的一动点,连接AD ,以AD为边向右作等边△ADE,连接CE,连接BE,△ABE的面积是否会随着点D的位置的变化而变化,如果变化,直接写出是如何变化的;如果不变,请说明理由.
(1)如图1,若D是边BC上的一动点,连接AD ,以AD为边向右作等边△ADE,连接CE,说明△ABD≌△ACE.
(2)若D是射线BC上的一动点,连接AD ,以AD为边向右作等边△ADE,连接CE,△ABC的边长为5,若CD=1,求CE.
(3)若D是射线BC上的一动点,连接AD ,以AD为边向右作等边△ADE,连接CE,连接BE,△ABE的面积是否会随着点D的位置的变化而变化,如果变化,直接写出是如何变化的;如果不变,请说明理由.
![](https://img.xkw.com/dksih/QBM/2020/10/15/2571509049925632/2572736333979648/STEM/c91310ab1fb94c1799d1d502a86eed88.png?resizew=497)
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【推荐2】如图,在△ABC中,∠A=90°,∠B=30°,AC=6cm,点D从点A以1cm/秒的速度向点C运动,点E从点C以2cm/秒的速度向点B运动,两点同时运动,同时停止,运动的时间为t秒,过点E作EF//AC交AB于点F.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/8/10/aa5a47c6-eac4-4cf6-b123-9adf76a788b6.png?resizew=135)
(1)当t为何值时,△DEC为等边三角形;
(2)当t为何值时,△DEC是直角三角形;
(3)求证:DC=EF;
(4)连接CF,当CF平分∠ACB时,直接写出AF与BF之间的数量关系.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/8/10/aa5a47c6-eac4-4cf6-b123-9adf76a788b6.png?resizew=135)
(1)当t为何值时,△DEC为等边三角形;
(2)当t为何值时,△DEC是直角三角形;
(3)求证:DC=EF;
(4)连接CF,当CF平分∠ACB时,直接写出AF与BF之间的数量关系.
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【推荐1】四边形
为平行四边形.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/10/30/acf0ecbc-1bbb-4160-aec9-73b277ffe26f.jpg?resizew=489)
(1)将平行四边形
沿对角线
翻折,点A落在点
处,连接
,
.
①如图1,延长
、
于点E,求证:
;
②如图2,若
,
交
于M,N为
上一点,直线
交
于P,满足
,试猜想
的值,并说明理由;
(2)如图3,点E是
边上的动点,己知
,现
,现将
沿
折叠,点
点是B的对应点,设
长为
,若点
落在
内(包括边界),直接写出
的取值范围为 .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/10/30/acf0ecbc-1bbb-4160-aec9-73b277ffe26f.jpg?resizew=489)
(1)将平行四边形
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d40b319212a7e7528b053e1c7097e966.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e7c314398e26ffc7164b82946eeb4273.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e663220a66eff19da6a71e46b397db2e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6a21897349d3d7c94419692106887153.png)
①如图1,延长
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/12daf5fea89631b84f896939c503d88a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9e52a8f07834cbbbe4224962672fbbb2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f2d9b69c9ccad8a244fc464ae70d93f7.png)
②如图2,若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8f89deb952f57f4b3fa4887b098b7b91.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6a21897349d3d7c94419692106887153.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411461db15ee8086332c531e086c40c7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e663220a66eff19da6a71e46b397db2e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/61e996453aadd3ab2e0654c6f34aa817.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9970ffead72bfa501cd0fce8918dec63.png)
(2)如图3,点E是
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/86422c276c537c810d243fbced9940d5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7099026716ee1821dd7d9f157dc055f5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e742966e3711cfa53dce04022acf4bcc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/68a83fdd2ba72a2dba0b6b10bb3e06b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3953cec61ac602ce5eb59b7912352179.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4eedae8d316c76e3d0b451256de03fb9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3953cec61ac602ce5eb59b7912352179.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a25c28359f8d8da9eaf4672a6cf8ae4f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
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【推荐2】已知:如图1,△ABC中,∠CAB=120°, AC=AB,点D是BC上一点,其中∠ADC=α(30°<α<90°),将△ABD沿AD所在的直线折叠得到△AED,AE交CB于F,连接CE
![](https://img.xkw.com/dksih/QBM/2022/4/15/2958580347797504/2959548068585472/STEM/27787b40-7745-42d7-8247-1ff6e6212f0a.png?resizew=490)
(1)求∠CDE与∠AEC的度数(用含α的代数式表示);
(2)如图2,当α=45°时,解决以下问题:
①已知AD=2,求CE的值;
②证明:DC-DE=
AD;
![](https://img.xkw.com/dksih/QBM/2022/4/15/2958580347797504/2959548068585472/STEM/27787b40-7745-42d7-8247-1ff6e6212f0a.png?resizew=490)
(1)求∠CDE与∠AEC的度数(用含α的代数式表示);
(2)如图2,当α=45°时,解决以下问题:
①已知AD=2,求CE的值;
②证明:DC-DE=
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cf298f00799cbf34b4db26f5f63af92f.png)
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【推荐1】综合与实践
【问题情境】
数学活动课上,老师出示了一个问题:如图(1),在
中,F为
的中点,E为边
上一点,连接
、
,连接
并延长交
的延长线于G,若
,试猜想
与
的位置关系,并加以证明.
(1)请解答老师提出的问题.
【实践探究】
(2)希望小组受此问题的启发,将
沿着
(F为
的中点)所在直线折叠,如图(2),点C的对应点为
,连接
并延长交
于点G,判断四边形
的形状,并加以证明.
【问题解决】
(3)如图3,智慧小组突发奇想,将
沿过点B的直线折叠,点A的对应点为
,使
于点H,
交
于点N,折痕交边
于点M.该小组提出一个问题:若
,
,直接写出
的面积.
【问题情境】
数学活动课上,老师出示了一个问题:如图(1),在
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5138a9f70d5e8b0580e30fef6eb7baef.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/49b50357a6545cae8348e3059312f520.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/85c4bdfb0db1e31e8459df1d15f9ab55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/274cf35acb4a1748d15c39d15a9bea7b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f586a2079d0e382ef843f4dbe068566e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/85c4bdfb0db1e31e8459df1d15f9ab55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
(1)请解答老师提出的问题.
【实践探究】
(2)希望小组受此问题的启发,将
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5138a9f70d5e8b0580e30fef6eb7baef.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/274cf35acb4a1748d15c39d15a9bea7b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b4c8a9c4957431681ddfc77895a88508.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/288abe01824f42cfe725509af5aec4cd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0895ad745ddcb4080a19a6275395ef7d.png)
【问题解决】
(3)如图3,智慧小组突发奇想,将
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5138a9f70d5e8b0580e30fef6eb7baef.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e7c314398e26ffc7164b82946eeb4273.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5128f894d192816321cabcecdff6c170.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e42198b8e646ccfbbec323fd364c4d90.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5b8b98b2f83279a49e94d9f48c5e6f2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b947acc328f9561e1d7b78f9bbed9263.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1445c7c8447641b27f8a4f69b22060c5.png)
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解题方法
【推荐2】如图,在平面直角坐标系中,点
为坐标原点,点
、
、
的坐标分别为
、
、
,
,将
沿着射线
翻折,点
落到
轴上点
处.
(1)求点
的坐标;
![](https://img.xkw.com/dksih/QBM/2021/9/8/2803441934376960/2804657383915520/STEM/e33ed5b4-6922-477b-99f9-350ad4a2056f.png)
(2)动点
以每秒1个单位长度的速度从点
出发沿着线段
向终点
运动,运动时间为
秒,请用含有
的式子表示
的面积,并直接写出
的取值范围;
![](https://img.xkw.com/dksih/QBM/2021/9/8/2803441934376960/2804657383915520/STEM/754a063e-54b6-49ed-99cc-39878d85efb0.png)
(3)在(2)的条件下,动点
以每秒2个单位长度的速度从点
出发沿着线段
向终点
运动,动点
以每秒
个单位长度的速度从点
出发沿着
轴正方向运动,点
、
、
同时出发;点
停止时,点
、
也停止运动,当
时,求
的值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.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/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/59f2be8f1e796226f1b0fa95f6aea35d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ea6122413ab3884330387df053e0b364.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dcbcd0aebdd8bd688d108834747009f5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fc34db5860990e51ba31edc8cdd077c2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0faed94a64b2dcfc6801b4fca0f16675.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d053b14c8588eee2acbbe44fc37a6886.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
(1)求点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://img.xkw.com/dksih/QBM/2021/9/8/2803441934376960/2804657383915520/STEM/e33ed5b4-6922-477b-99f9-350ad4a2056f.png)
(2)动点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/aaf1438142deeac876fc7dc50552e552.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/36a1b09c653185842513e24ebba60bb3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/36a1b09c653185842513e24ebba60bb3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5728d4c319e3612f86770e91aadf1997.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/36a1b09c653185842513e24ebba60bb3.png)
![](https://img.xkw.com/dksih/QBM/2021/9/8/2803441934376960/2804657383915520/STEM/754a063e-54b6-49ed-99cc-39878d85efb0.png)
(3)在(2)的条件下,动点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
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