角平分线性质定理描述了角平分线上的点到两边距离的关系,小明发现将角平分线放在三角形中,还可以得出一些线段比例的关系.
请完成下列探索过程:
【研究情景】
如图1,在△ABC中,∠ABC的角平分线交AC于点D.
【初步思考】
(1)若AB=4,BC=7,则
= ;
【深入探究】
(2)请判断
和
之间的数值关系,并证明;
【应用迁移】
(3)如图2,△ABC和△ECD都是等边三角形,△ABC的顶点A在△ECD的边ED上,CD交AB于点F,若AE=4,AD=2,求△CFB的面积.
请完成下列探索过程:
【研究情景】
如图1,在△ABC中,∠ABC的角平分线交AC于点D.
【初步思考】
(1)若AB=4,BC=7,则
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/30a7322178eb93db131c725008972ff7.png)
【深入探究】
(2)请判断
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2465ee1fec12351943f15055dfd6ec73.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/61f9215613b7b05217ed77268c238391.png)
【应用迁移】
(3)如图2,△ABC和△ECD都是等边三角形,△ABC的顶点A在△ECD的边ED上,CD交AB于点F,若AE=4,AD=2,求△CFB的面积.
![](https://img.xkw.com/dksih/QBM/2021/4/26/2707964849446912/2772375725441024/STEM/6740ba78b10a4d508f53e934b64e16f4.png?resizew=335)
20-21八年级下·四川成都·期中 查看更多[2]
更新时间:2021-07-26 08:35:45
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相似题推荐
解答题-证明题
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名校
【推荐1】如图,
、
、
均为直线
同侧的等边三角形.
![](https://img.xkw.com/dksih/QBM/2023/4/12/3214844833964032/3216429555548160/STEM/62b15e7878b941189c1bac19eeae75dc.png?resizew=328)
(1)如图①当
时,四边形
为 ;
(2)猜想:当
满足相应的条件:①
,②
其中一个时,顺次连接P、E、D、C四点所能构成的四边形是特殊平行四边形,选择其中的一种情况加以证明. 你选择的是:当满足条件 时,构成的四边形为 ,请写出证明过程.
(3)如图②,
中,
,
,请直接写出四边形
面积的最大值
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ab2a2834d80ff574e79eae8ca8d4e94f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/729684f958ad60b8e905fe1e1da53c03.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4234cf4d8159f5df0333bcc269ffe099.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://img.xkw.com/dksih/QBM/2023/4/12/3214844833964032/3216429555548160/STEM/62b15e7878b941189c1bac19eeae75dc.png?resizew=328)
(1)如图①当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a1647a5309dc8d4d12c40fd88bf10e30.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/df4b4815caaad872f4883d5c76678d6a.png)
(2)猜想:当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2205cffebf8c4d5f81d15ed7b85c8936.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63e4d19bf237a6fca67e0d01a9ddb726.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b59798989a286cbf711be156b28e6b0c.png)
(3)如图②,
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/af2cc5f8cec8c498aa12c99c04e1c97d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/080ca48cd27d4bf9d9ef084b558fc17a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9f9b9bb0f509e6f3d30858efb217c1f5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/df4b4815caaad872f4883d5c76678d6a.png)
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【推荐2】(1)如图1.四边形
是正方形,点
是
边上的一个动点,以
为边在
的右侧作正方形
,连接
、
,判断线段
与
的数量是__________;位置关系是__________.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/2/1/210b2900-5a3a-44b5-a8da-6b4e32b56e0f.png?resizew=161)
(2)如图2,四边形
是矩形,
,
,点
是
边上的一个动点,以
为边在
的右侧作矩形
,且
,连接
、
.判断线段
与
又有怎样的关系,并说明理由;
![](https://img.xkw.com/dksih/QBM/editorImg/2023/2/1/6f1f8422-955e-4f65-8136-51c2329c04e2.png?resizew=162)
(3)如图3,在(2)的条件下,连接
,点
是从点
运动到点
,直接写出点
的运动路径长度.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5cb3f9a5da641be35117fd35ba07a6aa.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/88929f4ba0851730d5f941d426b87548.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a6b41d4070854edfaa24071137b314cb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a6b41d4070854edfaa24071137b314cb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a8a2110034a1cf43218b1c54966547d7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7935ad59079c158ea0f92018fc548e4a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d0213c5787a5a6b38d11bceca5567f67.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7935ad59079c158ea0f92018fc548e4a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d0213c5787a5a6b38d11bceca5567f67.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/2/1/210b2900-5a3a-44b5-a8da-6b4e32b56e0f.png?resizew=161)
(2)如图2,四边形
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5cb3f9a5da641be35117fd35ba07a6aa.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d2c15801fee2405573677484f5dcfa4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/07160f14b3b453bebb64cb2bf96dc85a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/88929f4ba0851730d5f941d426b87548.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a6b41d4070854edfaa24071137b314cb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a6b41d4070854edfaa24071137b314cb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a8a2110034a1cf43218b1c54966547d7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ba2f500a59e94210d2689bbcd63696f0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7935ad59079c158ea0f92018fc548e4a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d0213c5787a5a6b38d11bceca5567f67.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7935ad59079c158ea0f92018fc548e4a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d0213c5787a5a6b38d11bceca5567f67.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/2/1/6f1f8422-955e-4f65-8136-51c2329c04e2.png?resizew=162)
(3)如图3,在(2)的条件下,连接
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/999a995a6d07c561ce64e8952994160a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/895dc3dc3a6606ff487a4c4863e18509.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/2/1/f0c8ef24-3261-4184-a713-119e55fc1111.png?resizew=174)
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【推荐1】如图,已知平行四边形ABCD中,∠ABC的平分线与边CD的延长线交于点E,与AD交于点F,且AF=DF,
①求证:AB=DE;
②若AB=3,BF=5,求△BCE的周长.
①求证:AB=DE;
②若AB=3,BF=5,求△BCE的周长.
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【推荐2】如图1,在平面直角坐标系中,直线
与
轴交于点
,与直线
交于点
.
(1)求
的值;
(2)点
是直线
上一动点.
①如图2,当点
恰好在
的角平分线上时,求直线
的函数表达式;
②是否存在点
,使得
,若存在,请求出点
的坐标;若不存在,请说明理由.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bbc9f6cf70f80f04167172247b747ce7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a841684ae8eb4ef3abcaa75ac85d11e7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2c53cfa785f3d78e95a3b170180fd4b4.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/9/20/e86d5e97-c220-4f16-8ad5-e366899bb064.jpg?resizew=318)
(1)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/294f5ba74cdf695fc9a8a8e52f421328.png)
(2)点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2e9b0f5f44abbc6544a2f672b025b013.png)
①如图2,当点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6d7b2fe01a33c4825f9974ed9663a99c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/683c590673eece14fea3319c4fd5eb55.png)
②是否存在点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e3e827be79b4aa00f23a78aa87b858a2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
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【推荐1】如图,等边
的边长为7cm,现有两动点M,N分别从点A、B同时出发,沿三角形的边按照图中标识的方向运动,已知点M的速度为1cm/s,点N的速度为2.5cm/s,当点N第一次到达点B时,点M、N同时停止运动.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/10/21/ef8b9a05-13dd-4237-bcf5-aec604c91232.png?resizew=401)
(1)点M、N运动几秒后,M、N两点重合?
(2)点M、N运动过程中,点M,N能否与
中的某一顶点构成等边三角形,若能求出对应的时间t,若不能请说明理由.
(3)当点M、N在边BC上运动时,连接AM、AN,能否得到以MN为底边的等腰三角形AMN?若能,请求出此时MN的边长,若不能请说明理由.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/10/21/ef8b9a05-13dd-4237-bcf5-aec604c91232.png?resizew=401)
(1)点M、N运动几秒后,M、N两点重合?
(2)点M、N运动过程中,点M,N能否与
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
(3)当点M、N在边BC上运动时,连接AM、AN,能否得到以MN为底边的等腰三角形AMN?若能,请求出此时MN的边长,若不能请说明理由.
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【推荐2】已知等边△ABC的边长为2,点D为边BC的中点,以点A为圆心的圆交边AC于点E(点E不与点A、C重合),
![](https://img.xkw.com/dksih/QBM/2022/4/14/2957843329867776/2958599576109056/STEM/fc596589-d0fd-4ad0-bae1-660ec0ae645c.png?resizew=172)
(1)如果圆A与线段BC有公共点,求线段AE的取值范围;
(2)如果射线DE与线段BA的延长线交于点F,
①设AE=x,AF=y,求y关于x的函数解析式,并写出函数定义域;
②当S△CDE=S△AEF时,求线段AE的长.
![](https://img.xkw.com/dksih/QBM/2022/4/14/2957843329867776/2958599576109056/STEM/fc596589-d0fd-4ad0-bae1-660ec0ae645c.png?resizew=172)
(1)如果圆A与线段BC有公共点,求线段AE的取值范围;
(2)如果射线DE与线段BA的延长线交于点F,
①设AE=x,AF=y,求y关于x的函数解析式,并写出函数定义域;
②当S△CDE=S△AEF时,求线段AE的长.
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【推荐1】定义:对角线相等的四边形称为对美四边形.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/8/24/38d36dba-f5a6-4329-9b96-e75dbaf43e59.png?resizew=370)
(1)我们学过的对美四边形有______、______.(写出两个)
(2)如图1,D为等腰
ABC底边AB上的一点,连结CD,过C作
,以B为顶点作
交CF于点E,求证:四边形CDBE为对美四边形.
(3)如图2,对美四边形ABCD中,对角线AC、BD交于点O,AC=BD,
.
①若
,
,求四边形ABCD的面积.
②若
,设
,
,试求出y与x的关系式.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/8/24/38d36dba-f5a6-4329-9b96-e75dbaf43e59.png?resizew=370)
(1)我们学过的对美四边形有______、______.(写出两个)
(2)如图1,D为等腰
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ce4cba95fc7d4853a243f8e3fb20ce70.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fe9f641563e8533a5bb39188aa7cc182.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3f80686918f2098cec4289caf3f71a84.png)
(3)如图2,对美四边形ABCD中,对角线AC、BD交于点O,AC=BD,
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e76526b18b736232d9c273a07904dbd.png)
①若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9ff5c21185c13eae675906dabd3593c7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/66a392569657cb71e80d0179ab16803c.png)
②若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60840a8920b8d5787e9916b0cf4605df.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2633a6f46b0847158eebb05c743561aa.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/531944b051cb8e0714370f050c5633f0.png)
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【推荐2】如图1,我们把对角线互相垂直的四边形叫做垂美四边形.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/4/5/99206e63-56b6-40b3-9d9d-2d7dd896f91e.png?resizew=444)
(1)判断:在平行四边形、矩形、菱形、正方形中,一定是垂美四边形的有 ;
(2)如图2,垂美四边形
两组对边
、
与
、
之间有怎样的数量关系?写出你的猜想,并给出证明;
(3)如图3,分别以
的直角边
和斜边
为边向外作正方形
和正方形
,连接
、
、
,
与
交于点O,已知
,
,求
的中线
的长.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/4/5/99206e63-56b6-40b3-9d9d-2d7dd896f91e.png?resizew=444)
(1)判断:在平行四边形、矩形、菱形、正方形中,一定是垂美四边形的有 ;
(2)如图2,垂美四边形
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
(3)如图3,分别以
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dd967903ed5a6f640a5b801ec8be0070.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ff7a0bfc593a8a33b6cade6ba213904c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ad3a079cfdcca9acdacecbf08f9f78cc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4eedae8d316c76e3d0b451256de03fb9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/06e322e0c87479bba874db9ae9ba36b5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/91f3956f008cc29ca4bae44a087d5427.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4eedae8d316c76e3d0b451256de03fb9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/06e322e0c87479bba874db9ae9ba36b5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d70dc2c20619a4fc12a0cfda59af5b69.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9f08273d339dc5ddbb89aa67bb8205e6.png)
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