1 . 【问题初探】
(1)综合与实践数学活动课上,张老师给出了一个问题:如图1,在
中,
,
,点D,E在BC边上,且
,求证:
.
①小明同学经过分析后,将
绕点A逆时针旋转
得到
,连接
,如图2,根据三角形全等和勾股定理知识得到线段
,
,
之间的数量关系;
②小强同学经过分析后,将
,
分别沿
,
进行翻折,得到
和
,如图3,根据三角形全等和勾股定理知识也得到了线段
,
,
之间的数量关系.
请你选择一名同学的分析,写出证明过程.
【类比分析】
(2)张老师发现两名同学分别从旋转和轴对称的角度分析、解决问题,张老师将前面问题进行变式,请你解答:如图4,在
中,
,
,点D在
边上,点E在
的延长线上,且
,用等式表示线段
,
,
之间的数量关系,并证明.
【学以致用】
(3)如图5,在四边形ABCD中,
,
,
.若
,
,
,求
的长.
(1)综合与实践数学活动课上,张老师给出了一个问题:如图1,在
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/047dc9795efa99b6fb9fdf9778085dab.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9c06154cae3bf7a8ce5a1e97a7380875.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c76805974fefbe166b90d260e822ab5a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/556dc413596019649298f7e8cf690a19.png)
①小明同学经过分析后,将
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ab2a2834d80ff574e79eae8ca8d4e94f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c02b54dc6b3e1bb6544f47d4c8743fcf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/54fb6e81fee5674c3e26a65e58cc506d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/49b50357a6545cae8348e3059312f520.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/e6e490f703eb6c9bb1278c78ebc2d661.png)
②小强同学经过分析后,将
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ab2a2834d80ff574e79eae8ca8d4e94f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dcb49df05f2e31d005735c3f14a21d30.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/68a83fdd2ba72a2dba0b6b10bb3e06b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d79c5041878c15de69253ca11a03ab1b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ca2698f08d94afa1cd5b81444791f4c7.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/e6e490f703eb6c9bb1278c78ebc2d661.png)
请你选择一名同学的分析,写出证明过程.
【类比分析】
(2)张老师发现两名同学分别从旋转和轴对称的角度分析、解决问题,张老师将前面问题进行变式,请你解答:如图4,在
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/047dc9795efa99b6fb9fdf9778085dab.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9c06154cae3bf7a8ce5a1e97a7380875.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/c76805974fefbe166b90d260e822ab5a.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/e6e490f703eb6c9bb1278c78ebc2d661.png)
【学以致用】
(3)如图5,在四边形ABCD中,
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2e735a28578ba191da6d4f3b0f8e8729.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/23b6e08fde74010412a6f14ad4dfbcc9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/192155e6a3aade305b76b1eb7c75e30c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/07140f277a35733d8c97577ccdd4e3ab.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/00948a72b7c367ccda6badc2f7ff22fa.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/56512504254ab7f574a717dd6830fb33.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/85c4bdfb0db1e31e8459df1d15f9ab55.png)
您最近一年使用:0次
2 . 【模型定义】
它是由两个共顶点且顶角相等的等腰三角形构成.在相对位置变化的同时,始终存在一对全等三角形.他们得知这种模型称为“手拉手模型”如果把小等腰三角形的腰长看作是小手,大等腰三角形的腰长看作大手,两个等腰三角形有公共顶点,类似大手拉着小手.
(1)如图
,若
和
均为等边三角形,点
、
、
在同一条直线上,连接
,则
的度数为 ;线段
与
之间的数量关系是 .
【模型应用】
(2)如图
,
,
,求证:
;
(3)如图
,
为等边
内一点,且
,以
为边构造等边
,这样就有两个等边三角形共顶点
,然后连接
,求
的度数是 .
【拓展提高】
(4)如图
,在
中,
,
,点
为
外一点,点
为
中点,
,
,求
的度数.(用含有m的式子表示)
(5)如图
,两个等腰直角三角形
和
中,
,
,
,连接
,
,两线交于点
,请证明
和
的数量关系和位置关系.
它是由两个共顶点且顶角相等的等腰三角形构成.在相对位置变化的同时,始终存在一对全等三角形.他们得知这种模型称为“手拉手模型”如果把小等腰三角形的腰长看作是小手,大等腰三角形的腰长看作大手,两个等腰三角形有公共顶点,类似大手拉着小手.
(1)如图
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bdaa19de263700a15fcf213d64a8cd57.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/90b40c2b0ab8e1cfe5112d428b4b829f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3a0acc93490a6a784eb62201d93dd93d.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/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/85c4bdfb0db1e31e8459df1d15f9ab55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1a55a1a244f81097e05e715b69580faa.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/85c4bdfb0db1e31e8459df1d15f9ab55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
【模型应用】
(2)如图
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/61128ab996360a038e6e64d82fcba004.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3570a95f68349fcd9417fcda62e78e7e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1a18d6c52c73deaf2e3cb979a9a1f03a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f7e6fc7fa79fbb093826e36845382db7.png)
(3)如图
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5ca7d1107389675d32b56ec097464c14.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ef81a8c9df79ad4a3ab754235f0b3ade.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2cdba1337ec85fa9722cb4b320a82ae6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/72b886208c6c2df19b984f2631e1c996.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/db54223bb3fc2fe2497213a4d1f94827.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cb686e4f5e3938575bc547e849d5513f.png)
【拓展提高】
(4)如图
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b8860d9787671b53b1ab68b3d526f5ca.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/047dc9795efa99b6fb9fdf9778085dab.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/edeeeb8cac599b8adf2f009c1366a6b4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2204145c88ed613f20f3024db9dbddfd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7a2907b8c21c74030b001f637ddfdc47.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1e31edc5b71c488ca9942d70d9298f01.png)
(5)如图
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d91e07104b699c4012be2d26160976a2.png)
![](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/047dc9795efa99b6fb9fdf9778085dab.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e30e50e094cd2849e38859b36aad0b0c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/26813466e2ee49a493881a4384fc8748.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/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d40b319212a7e7528b053e1c7097e966.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4eedae8d316c76e3d0b451256de03fb9.png)
您最近一年使用:0次
3 . 小明在学习矩形性质之后,对直角三角形的性质“直角三角形斜边上的中线等于斜边的一半”的证明思路做了深入的思考与总结.阅读小明的笔记,并完成相应任务.
定理:直角三角形斜边上的中线等于斜边的一半.
如图1,在
中,
,
是斜边
上的中线.
求证:
.
等于
的一半,可以用“倍长法”将
延长一倍,如图2,延长
到点
,使得
,连接
,只需通过证明三角形全等即可证明
.
证明:延长
到点
,使得
,连接
,如图2所示.
……
【问题解决】请根据小明的分析过程,在不添加其他辅助线的情况下,完成该定理的证明;
【问题再探】如图3,在
中,
于点
,
是边
的中线,
垂直平分
,若
,则
的度数为________;
【拓展提升】如图4,
,
是
的两条高,
,
分别是
,
的中点,若
,
,试求线段
的长.
定理:直角三角形斜边上的中线等于斜边的一半.
如图1,在
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/45acdbac251ca6b76a166c1242e71df9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d40b319212a7e7528b053e1c7097e966.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81aa5816176014df488313a050b8942b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d40b319212a7e7528b053e1c7097e966.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d40b319212a7e7528b053e1c7097e966.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d40b319212a7e7528b053e1c7097e966.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63f94cb32b388456ab9203e8d8b5309e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4eedae8d316c76e3d0b451256de03fb9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1120e471627069e78a6733af07687684.png)
证明:延长
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d40b319212a7e7528b053e1c7097e966.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63f94cb32b388456ab9203e8d8b5309e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4eedae8d316c76e3d0b451256de03fb9.png)
……
【问题解决】请根据小明的分析过程,在不添加其他辅助线的情况下,完成该定理的证明;
【问题再探】如图3,在
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.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/4eedae8d316c76e3d0b451256de03fb9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1e72b2e1ff83e95df048745322982451.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4eedae8d316c76e3d0b451256de03fb9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/34c23038cae3090dc99133bb6ddb3ea7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4598486f8c5ac28b1165b76e78105979.png)
【拓展提升】如图4,
![](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/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/54a5d7d3b6b63fe5c24c3907b7a8eaa3.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/07160f14b3b453bebb64cb2bf96dc85a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6933a9aed245548551418e737d2f062.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411461db15ee8086332c531e086c40c7.png)
您最近一年使用:0次
名校
4 . 折纸是一种常见的游戏,九年级兴趣小组以“矩形的折叠”为主题开展数学活动.
![](https://img.xkw.com/dksih/QBM/editorImg/2024/4/9/5f0c99de-9572-47a3-81af-770c97760b9b.png?resizew=449)
(1)操作判断:如图1,在矩形纸片
中,
,首先沿过点B的直线翻折,使点A落在
边上的点E处,折痕为
,连接
;此时,就可以得到一个四边形
,则四边形
的形状是哪种特殊的四边形?答:____.
(2)深入探究:继续沿过点E的直线翻折,使点C落在
边上的点G处,折痕为
,连接
,延长
交
于点M,连接
.
①求证:
;
②猜想线段
和
的数量关系,并证明;
(3)拓展应用:延长
交矩形
的边于点N,若
,直接写出
的值.
![](https://img.xkw.com/dksih/QBM/editorImg/2024/4/9/5f0c99de-9572-47a3-81af-770c97760b9b.png?resizew=449)
(1)操作判断:如图1,在矩形纸片
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b7c4e3cf5aa65a81a357c97a6b7ee5d7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/274cf35acb4a1748d15c39d15a9bea7b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/49b50357a6545cae8348e3059312f520.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2dde327febef2331a4766a79b433cc02.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2dde327febef2331a4766a79b433cc02.png)
(2)深入探究:继续沿过点E的直线翻折,使点C落在
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/49b50357a6545cae8348e3059312f520.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/589786dd7c3a2679c3230b671cd232d6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0d4b3a67756026228ce37056e00e5b97.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/06e322e0c87479bba874db9ae9ba36b5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4cae70b8a9d2d2e96dea62c00ced04b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8b46c607b3deac746c0ef3389ad8f65c.png)
①求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5d18e66f7066a1fdf2cb167a4862128c.png)
②猜想线段
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d96acb7106e9572759b31cb9b765b3af.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8b46c607b3deac746c0ef3389ad8f65c.png)
(3)拓展应用:延长
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/06e322e0c87479bba874db9ae9ba36b5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1ee2f46269ea85f3eb81c9a432814ac6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d546a5fbdf0496e6f563810d5bc4c627.png)
您最近一年使用:0次
5 . 如图1,在
中,点D,E分别在
,
上,
,点F在
上,
,
.
![](https://img.xkw.com/dksih/QBM/editorImg/2024/4/9/6f7c78aa-ff7e-4541-9a94-5f138e4aa5a7.png?resizew=300)
(1)在图1中找出与
相等的角并证明;
(2)求证:
;
(3)如图2,连接
,点M在
上,
,
,求
.(用含k的代数式表示)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3f5fc4ad65b723b6a8da4c8dac154e6e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/85c4bdfb0db1e31e8459df1d15f9ab55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c425de21534b7ac873756cd4a63f7e16.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a4dcecea81976284224fe219174d6a51.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2024/4/9/6f7c78aa-ff7e-4541-9a94-5f138e4aa5a7.png?resizew=300)
(1)在图1中找出与
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2f1a13346c7971d064ef14cecd9a9ed5.png)
(2)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/62ad08d2bfadadb5203a45b3d9e758a6.png)
(3)如图2,连接
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/00bab17635a999236e8d2e35017a208d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/49b50357a6545cae8348e3059312f520.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ca92ed4fa9f57071f1756a1e82c98ef0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b207b5a650034c5c75661af756f09a5e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/69f3445532f3a44a64a07792aafd062e.png)
您最近一年使用:0次
6 . 已知
,点
是射线
上一点,过点
作
,点
是平面内一动点(不与点
重合),连接
,将线段
绕点
顺时针旋转
,得到线段
(点
不与点
重合).连接
.取
的中点
,连接
.
![](https://img.xkw.com/dksih/QBM/editorImg/2024/4/4/eb4529c2-de0a-4574-bd9e-110dc3a3b72a.png?resizew=431)
(1)如图1,当点
落在线段
上时:
①求证:
;
②直接写出直线
与直线
相交所成的较小角的度数为______.
(2)如图2,当点
落在平面内其他位置时,
是否仍然成立?若成立,请就图2的情形给出证明;若不成立,请说明理由.
(3)若
,当点
在同一条直线上时,请直接写出线段
的长.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e252f4bc1975af1c7a775b46fab64ee5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7785afeeaf274892253d04b4f693b367.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9b14726ebb5e042007cf20f75eb01c74.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/be6a6301878fed2a01413020b27310a5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e6e490f703eb6c9bb1278c78ebc2d661.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/85c4bdfb0db1e31e8459df1d15f9ab55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/20a541b81584a032f571159ea152c85a.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2024/4/4/eb4529c2-de0a-4574-bd9e-110dc3a3b72a.png?resizew=431)
(1)如图1,当点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
①求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6015d15c7b1e1d38accc9af3741def42.png)
②直接写出直线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/20a541b81584a032f571159ea152c85a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/85c4bdfb0db1e31e8459df1d15f9ab55.png)
(2)如图2,当点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6015d15c7b1e1d38accc9af3741def42.png)
(3)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac5cb4c1a1e040c9432963a9a0f5f553.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d2fb188915d2e3d7bfd633fa18221b07.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/20a541b81584a032f571159ea152c85a.png)
您最近一年使用:0次
7 . 在中点复习课中,刘老师提出了如下问题:
![](https://img.xkw.com/dksih/QBM/editorImg/2024/3/29/34f59f50-8471-403e-a5c4-4bc3a8fecaad.png?resizew=359)
如图1,在
中,点D为
的中点,连接
,若
,求
的取值范围.
【初步分析】
小明经过分析,决定延长
到E,使
,连接
,可得到
,进而在
中得到
的取值范围,于是可求得
的取值范围.
(1)请回答:
①如图1,连接
,由已知和作图能得到
的理由是______.
A.
B.
C.
D.![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d5eb2decaa6be2df36a5e4b7fabf585d.png)
②求得
的取值范围是______.
A.
B.
C.
D.![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e0a6731ca8823b4b3d78367a1cb86f52.png)
【感悟探究】
小明经过反思发现,解题时,条件中若出现“中点”“中线”字样,可以考虑延长中线构造全等三角形,把分散的已知条件和所求证的结论集合到同一个三角形中.
于是小明尝试用这种方法证明“中位线定理”
如图2,
分别是
的边
的中点,求证:
,且
.
小明延长
至F,使
,连接
.
(2)请帮助小明完成证明.
【感悟拓展】
小明经过再次反思发现,解题时,条件中若出现多个“中点”字样,还可以考虑用中位线来研究中位线和三角形底边的数量关系和位置关系.请解决以下问题:
(3)如图3,在等边三角形
中,点P为射线
位于点C右侧的一个动点,将线段
绕点P逆时针旋转
得到线段
,点C的对应点为点D,连接
,点Q为
的中点,连接
.若
,当
时,直接写出
的长度.
![](https://img.xkw.com/dksih/QBM/editorImg/2024/3/29/34f59f50-8471-403e-a5c4-4bc3a8fecaad.png?resizew=359)
如图1,在
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.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/c8f83dded14ac36a1b267a52e0e8522d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
【初步分析】
小明经过分析,决定延长
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/df34369163e511f14028168cb0b21186.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/68a83fdd2ba72a2dba0b6b10bb3e06b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/af7d19b5c22d55256a532764d4a8a5b5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/80651f797ab9dccfd7163c605b091ad5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4eedae8d316c76e3d0b451256de03fb9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
(1)请回答:
①如图1,连接
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/85c4bdfb0db1e31e8459df1d15f9ab55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b30344bc4e9906892f903e1f0b691c18.png)
A.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6720e36b02193db161c61d4017673760.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5a290f047f50481318d040c604d72f7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9beb8b968744573e593ac28451c69729.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d5eb2decaa6be2df36a5e4b7fabf585d.png)
②求得
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
A.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cb89f323547493204e1550f32e94e9e2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/12b04633aebfef3b31813acf2f221355.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/288d232ff62a35acdf9bf8e706b95aa7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e0a6731ca8823b4b3d78367a1cb86f52.png)
【感悟探究】
小明经过反思发现,解题时,条件中若出现“中点”“中线”字样,可以考虑延长中线构造全等三角形,把分散的已知条件和所求证的结论集合到同一个三角形中.
于是小明尝试用这种方法证明“中位线定理”
如图2,
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/91e1e4115d78e625e9e0f47cdade3286.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e675a92cad72c65aa4071b9d9e226090.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/066cd386723885c535ea720f5817847a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0584568387d42bb65fff6fe354f1117a.png)
小明延长
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e6e490f703eb6c9bb1278c78ebc2d661.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2e9a9618018d717926540d1452f76e44.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/274cf35acb4a1748d15c39d15a9bea7b.png)
(2)请帮助小明完成证明.
【感悟拓展】
小明经过再次反思发现,解题时,条件中若出现多个“中点”字样,还可以考虑用中位线来研究中位线和三角形底边的数量关系和位置关系.请解决以下问题:
(3)如图3,在等边三角形
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/48f3c9abbd78e9a6840ee5f30381daac.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a6c0927afc571a7c966c98192040979e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e0629ce42392a7fe9be21d25c39c3e64.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d40b319212a7e7528b053e1c7097e966.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d40b319212a7e7528b053e1c7097e966.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f53330c107f8245290a5a42c3d356acd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/efc6e4b936d7a800e839a30c3839574d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/809f2107a6172278be8675645f1c186d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2cdba1337ec85fa9722cb4b320a82ae6.png)
您最近一年使用:0次
2024九年级下·浙江·专题练习
8 . 如图1,在
中,
,点
、
分别在边
、
上,
,连接
,点
、
、
分别为
、
、
的中点,连接
,
.
;
(2)当
绕点
旋转到如图2所示的位置时,
①
是否仍然成立?若成立请证明;若不成立,说明理由;
②若
,
和
的面积分别是
,
,
的面积为
,求
的值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b3c65edad25ddd666cdce0d7e5afefc9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/047dc9795efa99b6fb9fdf9778085dab.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.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/e2d212c1709b8e72a055cf1b5381ef64.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9e52a8f07834cbbbe4224962672fbbb2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/895dc3dc3a6606ff487a4c4863e18509.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e6e490f703eb6c9bb1278c78ebc2d661.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9e52a8f07834cbbbe4224962672fbbb2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b5c2293f93791a597bf0162411f3395f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4505508b3e36db64a207dcdaf8eb22dc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c3c3ae80011ff3bf3a4e2fe452666060.png)
(2)当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a25c28359f8d8da9eaf4672a6cf8ae4f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
①
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c3c3ae80011ff3bf3a4e2fe452666060.png)
②若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0e6648783311af7c86e8673f9d9ba996.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/95558cdc4ce1e6d9462d2e91c070655f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4c12dce7515929ec36491234a6760c57.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/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6899bf9cadae2ccdb14cbc87d4f280ee.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4cc80d8bbc5fec873686719e78bd518d.png)
您最近一年使用:0次
9 . 如图,在正方形
中,点M是
边上的任一点,连接
并将线段
绕点M顺时针旋转
得到线段
,在
边上取点P使
,连接
、
.
;
(2)线段
与
交于点Q,连接
,若
,证明:
;
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d50703c46b6153945d718b198f03b4b5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d50703c46b6153945d718b198f03b4b5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c02b54dc6b3e1bb6544f47d4c8743fcf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411461db15ee8086332c531e086c40c7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/da80b21960e7eb7651816ae73e17e12f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5845ffc7d1af9053b027cf9e726f5367.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2cdba1337ec85fa9722cb4b320a82ae6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2eef15ff8a5d06b65a2485cc74f65587.png)
(2)线段
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411461db15ee8086332c531e086c40c7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/84d454c82d9e52747563d47b68099249.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ebc82c74b0f1d873614690816b1e9548.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8361ee004d1e0716806b41a637a09c8a.png)
您最近一年使用:0次
名校
10 . 已知:在
中,
,
,
是
边上的动点,将线段
绕点
顺时针旋转
得到线段
.
在线段
上时,求证:
是
的中点;
(2)如图2,连接
,取线段
的中点
,连接
,直接写出
的大小并证明;
(3)若
是
的中点,
,直接写出
的最小值为______.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/047dc9795efa99b6fb9fdf9778085dab.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0fffa3d9c32da53b0ea0c338012ea20c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/be6a6301878fed2a01413020b27310a5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e6e490f703eb6c9bb1278c78ebc2d661.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
(2)如图2,连接
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/85c4bdfb0db1e31e8459df1d15f9ab55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/85c4bdfb0db1e31e8459df1d15f9ab55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d50703c46b6153945d718b198f03b4b5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0023e53eafba27ad50f9a9d3a4207d70.png)
(3)若
![](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/07160f14b3b453bebb64cb2bf96dc85a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/49b50357a6545cae8348e3059312f520.png)
您最近一年使用:0次
2024-03-24更新
|
250次组卷
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