如图所示,已知
与
相交于点F,
平分
,
平分
,试说明
三者之间的数量关系.
![](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/85c4bdfb0db1e31e8459df1d15f9ab55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5d59511c474942171fb685fc3f8dfd2d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e6e490f703eb6c9bb1278c78ebc2d661.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3981e7286d41960daf4e110c1c84e03a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/01f40207854bffec281ba1dbdf9b1dda.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/4/29/c0d8e771-9a84-4fb0-8633-bbcb1f82b378.png?resizew=140)
2023七年级下·上海·专题练习 查看更多[1]
(已下线)重难点02 三角形(五种模型)-【满分全攻略】2022-2023学年七年级数学下学期核心考点+重难点讲练与测试(沪教版)
更新时间:2023-04-23 14:53:24
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相似题推荐
解答题-问答题
|
较难
(0.4)
【推荐1】如图,直线
与直线
相交于点O,
. 已知
,
绕点O在平面内旋转,旋转前,边
与射线
重合,边
与射线
重合. 将
绕点O按每秒
的速度沿顺时针方向旋转一周.
![](https://img.xkw.com/dksih/QBM/editorImg/2024/1/23/3d3ed9e2-1126-41a2-8a5a-360b26346e04.png?resizew=375)
(1)如图1,从
旋转开始至
边与射线
重合时,共需多少秒?
(2)
旋转至如图2所示位置时,试说明
与
有何数量关系,并说明理由;
(3)如图3,已知
,
绕点O在平面内旋转,旋转前,边
与射线
重合,边
与射线
重合. 若在
旋转过程中,
绕点O以每秒
的速度绕点O沿逆时针方向旋转,当
停止旋转时,
也停止旋转,旋转过程中,当边
所在直线恰好平分锐角
时,求出旋转时间.
![](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/79684a6e92297749c005e2b23cac9710.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/14b5d523373b8cbfa33e42a1bf154544.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/27935c1ef4df2d52ac697678a3c8f39d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/aaf3369e0ea90e8d5cf4b6b3c45c0fd8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b90e0f35eda1a729fed485f83da5ea9d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/88e9f7d1272b7344346b58b660aa260a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/683c590673eece14fea3319c4fd5eb55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/27935c1ef4df2d52ac697678a3c8f39d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bab234099db50b451eb6ec2d5b21fe1f.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2024/1/23/3d3ed9e2-1126-41a2-8a5a-360b26346e04.png?resizew=375)
(1)如图1,从
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/27935c1ef4df2d52ac697678a3c8f39d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/88e9f7d1272b7344346b58b660aa260a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/828628c0876b45381c9a0edeb0fec236.png)
(2)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/27935c1ef4df2d52ac697678a3c8f39d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6463e5b629f54a517050d1327580aa5b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f92f279be7c8a11dcd2c0a97116bdcbb.png)
(3)如图3,已知
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81966a1b8c376ed64e8238b7794f439c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/10aa98b163ade82dcadbe8dd3b73e42e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/abd13974aebe38eb2a1d744a01ea5aa5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/828628c0876b45381c9a0edeb0fec236.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9f0009063fe00277645aff1be6e32471.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ef4113c492885ba7c47fe42ac792578f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/27935c1ef4df2d52ac697678a3c8f39d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/10aa98b163ade82dcadbe8dd3b73e42e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/654c79a470d5af5e0a34fd9233da5118.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/27935c1ef4df2d52ac697678a3c8f39d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/10aa98b163ade82dcadbe8dd3b73e42e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/88e9f7d1272b7344346b58b660aa260a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/10aa98b163ade82dcadbe8dd3b73e42e.png)
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名校
【推荐2】探索新知:如图1,射线OC在∠AOB的内部,图中共有3个角:∠AOB,∠AOC和∠BOC,若其中有一个角的度数是另一个角度数的两倍,则称射线OC是∠AOB的“巧分线”.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/9/19/b6c56cba-5a73-4195-943b-0bc79e7059e0.png?resizew=412)
(1)一个角的平分线 这个角的“巧分线”;(填“是”或“不是”)
(2)如图2,若∠MPN=x,且射线PQ是∠MPN的“巧分线”,则∠MPQ= ;(用含x的代数式表示出所有可能的结果)
(3)深入研究:如图2,若∠MPN=60°,且射线PQ绕点P从PN位置开始,以每秒10°的速度逆时针旋转,当PQ与PN成180°时停止旋转,旋转的时间为t秒.当t为何值时,射线PM是∠QPN的“巧分线”;
![](https://img.xkw.com/dksih/QBM/editorImg/2022/9/19/b6c56cba-5a73-4195-943b-0bc79e7059e0.png?resizew=412)
(1)一个角的平分线 这个角的“巧分线”;(填“是”或“不是”)
(2)如图2,若∠MPN=x,且射线PQ是∠MPN的“巧分线”,则∠MPQ= ;(用含x的代数式表示出所有可能的结果)
(3)深入研究:如图2,若∠MPN=60°,且射线PQ绕点P从PN位置开始,以每秒10°的速度逆时针旋转,当PQ与PN成180°时停止旋转,旋转的时间为t秒.当t为何值时,射线PM是∠QPN的“巧分线”;
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名校
解题方法
【推荐1】在△ABC中,∠C>∠B.如图①,AD⊥BC于点D,AE平分∠BAC.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/1/3/6f9ffc2f-f1b4-43b6-bf11-f8c0ff8e3055.png?resizew=437)
(1)如图①,∠B=30°,∠C=40°,则∠DAE= .
(2)如图①,∠B=40°,∠C=80°,则∠DAE= .
(3)由(1)(2)能猜想出∠DAE与∠B、∠C之间的关系是什么?并说明理由.
(4)如图②,AE平分∠BAC,F为AE上的一点,且FD⊥BC于点D,这时∠EFD与∠B、∠C有何数量关系?请说明理由.
(5)如图③,AE平分∠BAC,F为AE延长线上的一点,FD⊥BC于点D,请你写出这时∠EFD与∠B、∠C之间的数量关系(只写结论,不必说明理由).
![](https://img.xkw.com/dksih/QBM/editorImg/2023/1/3/6f9ffc2f-f1b4-43b6-bf11-f8c0ff8e3055.png?resizew=437)
(1)如图①,∠B=30°,∠C=40°,则∠DAE= .
(2)如图①,∠B=40°,∠C=80°,则∠DAE= .
(3)由(1)(2)能猜想出∠DAE与∠B、∠C之间的关系是什么?并说明理由.
(4)如图②,AE平分∠BAC,F为AE上的一点,且FD⊥BC于点D,这时∠EFD与∠B、∠C有何数量关系?请说明理由.
(5)如图③,AE平分∠BAC,F为AE延长线上的一点,FD⊥BC于点D,请你写出这时∠EFD与∠B、∠C之间的数量关系(只写结论,不必说明理由).
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【推荐2】【问题背景】
三角形和四边形是我们熟悉的几何图形,我们知道三角形内角和
,四边形的内角和是
.
【问题思考】
如图1,在
中,延长
到点D,
,
分别平分
和
.
,
,求
的度数;
(2)设
,
,x与y都是变量,但x与y的和是个常量,即
,m是常量.在x与y变化的过程中,
的大小是否变化,若不变,请直接写出用含m的代数式表示
;若变化,请说明理由.
【问题拓展】
在四边形
中,设
,
,延长
到点E,
,
分别平分
和
.
(3)如图2,当
,此时
,
的位置关系为 ;
(4)如图3,当
,
,
所在直线交于点N,请说明
与α,β的数量关系;
(5)将(4)中的条件
改为
,其余条件不变,请画出简图,并直接写出
与α,β的数量关系.
三角形和四边形是我们熟悉的几何图形,我们知道三角形内角和
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bfe639eab78eafd2d40ea70aa5d3f21d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1b2ccc34a8b3cf908af78bdbe804afac.png)
【问题思考】
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/d50703c46b6153945d718b198f03b4b5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e69d2b798744645af88a4fa411344a83.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/21b28f28ced0531d1df34fcf04c6c67f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/76bc8e50eeccced1d7f3bc52e09a7d03.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fa6ea7731f1311d265ed13d54d069cbd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d8bdacc1fd3aa36d65a4d00455238a29.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b2f9c3b578fc0598d5ec6c79404c6cc2.png)
(2)设
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/90f2209c4fe897cfb3a5ef7012d0502a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/129d8ebdb97266e0f835dff5af788200.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7324eb84ef5685b4a0fd7866858025d8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b2f9c3b578fc0598d5ec6c79404c6cc2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b2f9c3b578fc0598d5ec6c79404c6cc2.png)
【问题拓展】
在四边形
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3202b1d9f838c32ab5765ce647d96b6e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/12ea718698b44ab67a5dac6206e54f0d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/20a541b81584a032f571159ea152c85a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cb6ede9761b5b90f8dc137708e1ee90f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4189a0821a0ffab9dc171ecd279ba442.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2d29e7c4d6216690152430b09f9cf0c2.png)
(3)如图2,当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3cc18d7c5f9903ab90e40b0d9d62b105.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/20a541b81584a032f571159ea152c85a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cb6ede9761b5b90f8dc137708e1ee90f.png)
(4)如图3,当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d6db901868524464ef016565f59cbda2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/20a541b81584a032f571159ea152c85a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cb6ede9761b5b90f8dc137708e1ee90f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/274e29821dd4630a7182573b7c654f1f.png)
(5)将(4)中的条件
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d6db901868524464ef016565f59cbda2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b7b76dbad5ee0d2732c5d4984e5a2caa.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/274e29821dd4630a7182573b7c654f1f.png)
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