已知:在Rt△ABC中,AB=BC,在Rt△ADE中,AD=DE;连结EC,取EC的中点M,连结DM和BM.
(1)若点D在边AC上,点E在边AB上且与点B不重合,如图1,
求证:BM=DM且BM⊥DM;
(2)如果将图1中的△ADE绕点A逆时针旋转小于45°的角,如图2,那么(1)中的结论是否仍成立?如果不成立,请举出反例;如果成立,请给予证明.
(1)若点D在边AC上,点E在边AB上且与点B不重合,如图1,
求证:BM=DM且BM⊥DM;
(2)如果将图1中的△ADE绕点A逆时针旋转小于45°的角,如图2,那么(1)中的结论是否仍成立?如果不成立,请举出反例;如果成立,请给予证明.
更新时间:2018-05-08 19:39:59
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解答题-问答题
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解题方法
【推荐1】问题提出
(1)如图①,在
中,
,
于点
,若
,求
的最大值;
问题探究
(2)如图②,在四边形
中,
.连接
,求
面积的最大值.
问题解决
(3)如图③,某市郊区点
外有一棵古树,点
外是某市古树名木保护研究中心,且
,为加强对该古树的检测和保护,拟在距古树
处设置三个观测点
,以形成保护区域四边形
.则是否存在一个满足以上要求的面积最大的四边形
?若存在,求出满足条件的四边形
的最大面积;若不存在,请说明理由.(研究中心及各观测点的占地面积忽略不计)
(1)如图①,在
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0faed94a64b2dcfc6801b4fca0f16675.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9c06154cae3bf7a8ce5a1e97a7380875.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8b5f215a42c4b7078d8d65923eb9980e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e65a3e478bb87d094e3a0af30dd10ae8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
问题探究
(2)如图②,在四边形
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4cda8c37ccaf2ba95c4d32402b5c7e22.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d40b319212a7e7528b053e1c7097e966.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7df6d51738ac1bc8b9530ea4a55745c2.png)
问题解决
(3)如图③,某市郊区点
![](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/ae0c8a38c463a5fc0da9870668319322.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c65cce51b851717ccbd705588d77802b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/28855a0db693584aabac1df99dfade3d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://img.xkw.com/dksih/QBM/2021/5/28/2730696399003648/2733702222839808/STEM/468bc873-9aba-4c4f-8eb7-68a701764745.png)
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【推荐2】如图,正方形OABC的边OA,OC在坐标轴上,点B的坐标为
.点P从点A出发,以每秒2个单位长度的速度沿x轴向点O运动;点Q从点O同时出发,以相同的速度沿x轴的正方向运动,规定点P到达点O时,点Q也停止运动.连接BP,过P点作BP的垂线,与过点Q平行于y轴的直线
交于点D.BD与y轴交于点E,连接PE.设点P运动的时间为
.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/15/2e828373-2d68-4acf-98e3-62e1909eff96.png?resizew=191)
(1)求证:
.
(2)直接写出:
的度数为______,点D的坐标为______(用t表示).
(3)当t为何值时,
为等腰三角形?
(4)探索
周长是否随t变化而变化?若变化,说明理由;若不变,求这个定值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a78e50fb129fdd39104e3fb5893b1f80.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0f85fca60a11e1af2bf50138d0e3fe62.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9ecd76012d1b9c5e9fec6221e6e489c2.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/15/2e828373-2d68-4acf-98e3-62e1909eff96.png?resizew=191)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/29115855d29e029f248fc90365b13b57.png)
(2)直接写出:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3e98f2e85bdf9c6669c14f8966ed53be.png)
(3)当t为何值时,
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9b6accdd9b317c922d335e44911df357.png)
(4)探索
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08b98bec817e96fba365ba496ad3b9af.png)
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解题方法
【推荐1】综合与实践
探索发现:
如图1,在
中,
,
,点D为直线BC上一动点(点D不与B,C重合),点F在直线AB上,且
,将AD绕点D顺时针旋转
得到ED,连接BE.
(1)当点D在线段BC上,且
时,AF与BE之间的数量关系为: ;
拓展探究:
(2)如图2,当点D在线段BC上,且
时,请判断AF与BE之间的数量关系,并说明理由;
解决问题:
(3)在
中,若
,
,点D在射线BC上,将线段AD绕点D顺时针旋转
得到线段ED,连接BE,当
时,请直接写出BE的长.
探索发现:
如图1,在
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4b10134e7a46e6f6f7cb9d5e2371727d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c029e4ab80f8a2080d59ba73841f364f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9ccaba00766e9b03572655ea18bb7372.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e170f206fdbbd834aad7580c727e2cc6.png)
(1)当点D在线段BC上,且
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/33ac762a2899a58faa0d3ab44f1281fa.png)
拓展探究:
(2)如图2,当点D在线段BC上,且
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/708d48b595c17d4dccf9b4086d7e664e.png)
解决问题:
(3)在
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d30f9b7a6123f13fa0793ead76dc651a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a1be17e0a3e51cde1f50f384198e71e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a6c0927afc571a7c966c98192040979e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8a7e75d7342e6f087370d09181b17a4e.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/11/5/a2a8c06e-a826-407e-9f84-1ff034977131.png?resizew=427)
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【推荐2】如图,已知在
中,
,
,点
为边
上的一点,点
为线段
上一点.
,延长
交
于点
,
边的高
交
于点
.
①若
为
的平分线,求证:
;
②若
为
的中线,连接
,求证:
.
(2)如图(2),若
且
,过点
作
,交
延长线于点
,过点
作
于
,求
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)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e1a9c6a736e6eac98a676fa3232db5a5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b3182db896bc2462331796e2a6108363.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/53c51c25b65a37b676ae3c3b71c29f9b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b9f79d7939c88e9702962e5917cad290.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/764509115979e9958101808383672ec0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/764509115979e9958101808383672ec0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/db7ea03277f8408fabe5b327cc34838f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b3182db896bc2462331796e2a6108363.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/73465a1f9aa03481295bf6bd3c6903ac.png)
①若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b3182db896bc2462331796e2a6108363.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d39b8d91afc34e4a9b0fdbb6bafb9087.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/42a6e0f9874c0bc6861343ce496e736d.png)
②若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b3182db896bc2462331796e2a6108363.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a679040c4d556723e482bacbab41356d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/469938d20b4ecd9b69fdb5f497115078.png)
(2)如图(2),若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6d42e97eee705d164e6ac6de9ecd6d1f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e30e50e094cd2849e38859b36aad0b0c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ef5c475c18c418395b181d5acbec0700.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b9f79d7939c88e9702962e5917cad290.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fbeea2de356d06bafa2359de1a482a29.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/acc290b44635265137fdf13146b6a6d9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3a92b325ffa3486e093884f0b99c9463.png)
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【推荐1】如图,四边形ABCD中,AD//BC,∠ADC=90°,AD=8,BC=CD=6,点M从点D出发,以每秒2个单位长度的速度向点A运动,同时,点N从点B出发,以每秒1个单位长度的速度向点C运动.当其中一个动点到达终点时,另一个动点也随之停止运动.过点N作NP⊥AD于点P,连接AC交NP于点Q,连接MQ,设运动时间为t秒(
).
(2)当NP经过线段AC中点时,求t的值并直接写出此时线段MQ、NQ的关系;
(3)连接AN、CP,在点M、N运动过程中,是否存在某一时刻t,使四边形ANCP的面积与四边形ABNP的面积相等?若存在,求出t的值;若不存在,请说明理由;
(4)将△AQM沿AD翻折,得到△AKM.在点M、N运动过程中,
①是否存在某时刻t,使四边形AQMK为菱形?若存在,求出t的值;若不存在,请说明理由;
②是否存在某时刻t,使四边形AQMK为正方形?若存在,求出t的值;若不存在,请说明理由.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0c0fed6f944ef4b07f7e33ca893581fa.png)
(2)当NP经过线段AC中点时,求t的值并直接写出此时线段MQ、NQ的关系;
(3)连接AN、CP,在点M、N运动过程中,是否存在某一时刻t,使四边形ANCP的面积与四边形ABNP的面积相等?若存在,求出t的值;若不存在,请说明理由;
(4)将△AQM沿AD翻折,得到△AKM.在点M、N运动过程中,
①是否存在某时刻t,使四边形AQMK为菱形?若存在,求出t的值;若不存在,请说明理由;
②是否存在某时刻t,使四边形AQMK为正方形?若存在,求出t的值;若不存在,请说明理由.
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【推荐2】如图,△ABC是边长为5的等边三角形,P是线段AB上一动点,由A点向B点运动(点P与A、B点不重合),Q是BC延长线上一点,与点P同时以相同的速度由C向BC延长线方向运动(Q不与C点重合,当P点到达终点时,Q点停止运动),过P作PE⊥AC于点E,连接PQ交AC于点D.
![](https://img.xkw.com/dksih/QBM/2022/4/19/2961648100589568/2977293779058688/STEM/b4658d9295cd4498bcd43550c0a84b65.png?resizew=260)
![](https://img.xkw.com/dksih/QBM/2022/4/19/2961648100589568/2977293779058688/STEM/9597e9db6b634a08814dc12f92a89141.png?resizew=264)
(1)当∠APD=90°时,求AP的长 ;
(2)求证:在点P、Q运动过程中,PD与QD相等;
(3)在点P、Q运动时,线段ED的长是否发生变化?如果改变,求出变化范围;如果不变,说明理由并求出这个值.
![](https://img.xkw.com/dksih/QBM/2022/4/19/2961648100589568/2977293779058688/STEM/b4658d9295cd4498bcd43550c0a84b65.png?resizew=260)
![](https://img.xkw.com/dksih/QBM/2022/4/19/2961648100589568/2977293779058688/STEM/9597e9db6b634a08814dc12f92a89141.png?resizew=264)
(1)当∠APD=90°时,求AP的长 ;
(2)求证:在点P、Q运动过程中,PD与QD相等;
(3)在点P、Q运动时,线段ED的长是否发生变化?如果改变,求出变化范围;如果不变,说明理由并求出这个值.
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【推荐1】如图1,有等边
和等边
,将
绕点A顺时针旋转,得到图2所示的图形.
(1)求证:
;
(2)如图3,若
,
,且旋转角为
时,求
的度数;
(3)如图4,连接
,并延长
交
于点F,若
旋转至某一位置时,恰有
,
,求
的值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a25c28359f8d8da9eaf4672a6cf8ae4f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a25c28359f8d8da9eaf4672a6cf8ae4f.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/8/3/d8e17488-059a-46a7-84bf-94018e86abdf.png?resizew=458)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/52273305805769a438772342b53c289e.png)
(2)如图3,若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/684d2bbdd30443a7b73738d051d9a5dd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9e219b4b74587a077f223fec499bace9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/79a97bb4dcfab4ec7539bc783d563c49.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/86a2db6311e228ed33b6c71d0a5918cf.png)
(3)如图4,连接
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/85c4bdfb0db1e31e8459df1d15f9ab55.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/a25c28359f8d8da9eaf4672a6cf8ae4f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/650c6c818df102a83ce5159e3208d01a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8dfa223e7b272346649538457c976864.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9f692d0437e200690eabcd84ebcfa8a9.png)
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解题方法
【推荐2】在Rt△ABC中,∠ACB=90°,tan∠BAC=
.点D在边AC上(不与A,C重合),连结BD,F为BD中点.
![](https://img.xkw.com/dksih/QBM/2020/8/23/2534007953514496/2558534881263616/STEM/85b47500a0a940b7ba18b2afe9e71848.png?resizew=431)
(1)若过点D作DE⊥AB于E,连结CF、EF、CE,如图1.设CF=kEF,则k= ;
(2)若将图1中的△ADE绕点A旋转,使得D、E、B三点共线,点F仍为BD中点,如图2.求证:BE-DE=2CF;
(3)若BC=6,点D在边AC的三等分点处,将线段AD绕点A旋转,点F始终为BD中点,求线段CF长度的取值范围.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f89eef3148f2d4d09379767b4af69132.png)
![](https://img.xkw.com/dksih/QBM/2020/8/23/2534007953514496/2558534881263616/STEM/85b47500a0a940b7ba18b2afe9e71848.png?resizew=431)
(1)若过点D作DE⊥AB于E,连结CF、EF、CE,如图1.设CF=kEF,则k= ;
(2)若将图1中的△ADE绕点A旋转,使得D、E、B三点共线,点F仍为BD中点,如图2.求证:BE-DE=2CF;
(3)若BC=6,点D在边AC的三等分点处,将线段AD绕点A旋转,点F始终为BD中点,求线段CF长度的取值范围.
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