如图1,点A、B分别在射线OM、ON上运动(不与点O重合),AC、BC分别是∠BAO和∠ABO的角平分线,BC延长线交OM于点G.
(1)若∠MON=60°,则∠ACG= ;(直接写出答案)
(2)若∠MON=n°,求出∠ACG的度数;(用含n的代数式表示)
(3)如图2,若∠MON=x°,过点C作CF∥OA交AB于点F,求∠BGO-∠ACF的度数.(用含x的代数式表示)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/11/2/e56aaad0-c6c0-4d8b-bf7a-8e0c8d9d64b6.png?resizew=327)
(1)若∠MON=60°,则∠ACG= ;(直接写出答案)
(2)若∠MON=n°,求出∠ACG的度数;(用含n的代数式表示)
(3)如图2,若∠MON=x°,过点C作CF∥OA交AB于点F,求∠BGO-∠ACF的度数.(用含x的代数式表示)
20-21八年级上·江苏无锡·阶段练习 查看更多[3]
江苏省无锡市胡埭中学2020-2021学年八年级9月月考数学试题(已下线)【南昌新东方】2020年-11月-江西南昌-十校联考-初二-第一学期-期中-数学-试卷 9(已下线)【南昌新东方】 2020年南昌一中八年级上期中试卷
更新时间:2020-10-23 21:33:15
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解答题-证明题
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【推荐1】(1)如图1,已知
,B在
上,D在
上,点E在两平行线之间,求证:![](https://staticzujuan.xkw.com/quesimg/Upload/formula/19d50223d62daf2bba415887ed5cb005.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/30/96ee905a-a02d-488e-827a-96047c72e5e7.png?resizew=489)
(2)如图2,已知
,B在
上,C在
上,A在B的左侧,D在C的右侧,
平分
,
平分
,直线
、
交于点E,
.
①若
,求
的度数.
②将线段
沿
方向平移,使得点D在点C的左侧,其他条件不变,如图3所示.若
,则
的度数是________度(用关于n的代数式表示).
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ee73b155effcaeba36c8a460d549e097.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411461db15ee8086332c531e086c40c7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7a5f1641947153c80b987320885a2b57.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/19d50223d62daf2bba415887ed5cb005.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/30/96ee905a-a02d-488e-827a-96047c72e5e7.png?resizew=489)
(2)如图2,已知
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ee73b155effcaeba36c8a460d549e097.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411461db15ee8086332c531e086c40c7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7a5f1641947153c80b987320885a2b57.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/85c4bdfb0db1e31e8459df1d15f9ab55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d39b8d91afc34e4a9b0fdbb6bafb9087.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e6e490f703eb6c9bb1278c78ebc2d661.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/85c4bdfb0db1e31e8459df1d15f9ab55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/161b7b71b91aef8fc47fec4252cf412d.png)
①若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d17ba7617bbcd51f4f7a87c2fe175769.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/eb3de20ba8bda63c650ef571be155702.png)
②将线段
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9e52a8f07834cbbbe4224962672fbbb2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/34d4ce61435991179003c34240ba6ee1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/eb3de20ba8bda63c650ef571be155702.png)
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解题方法
【推荐2】如图①,已知AB∥CD,一条直线分别交AB、CD于点E、F,∠EFB=∠B,FH⊥FB,点Q在BF上,连接QH.
(1)已知∠EFD=70°,求∠B的度数;
(2)求证: FH平分∠GFD.
(3)在(1)的条件下,若∠FQH=30°,将△FHQ绕着点F顺时针旋转,如图②,若当边FH转至线段EF上时停止转动,记旋转角为α,请直接写出当α为多少度时,QH与△EBF的某一边平行?
(1)已知∠EFD=70°,求∠B的度数;
(2)求证: FH平分∠GFD.
(3)在(1)的条件下,若∠FQH=30°,将△FHQ绕着点F顺时针旋转,如图②,若当边FH转至线段EF上时停止转动,记旋转角为α,请直接写出当α为多少度时,QH与△EBF的某一边平行?
![](https://img.xkw.com/dksih/QBM/editorImg/2023/8/30/8f2eb6a3-53a4-4ac9-852b-5f0e37228dac.png?resizew=131)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/8/30/be40acf2-9d10-4cd4-9246-e945742126ab.png?resizew=138)
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【推荐1】如图,已知
,点E在直线
与
之间.
(1)如图1,求证:
(2)如图2,
和
的平分线交于点F,若
比
大
,求
的度数.
(3)如图3,
,连接
,过点E作
于点H,
和
的平分线分别交
和
于M,N.若
,
,请直接写出
的大小_________.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b0fff774b4b0087a6f304ce930d359be.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2024/3/27/58819ee1-70b0-4711-a39b-1f0b3a3e0ba7.png?resizew=354)
(1)如图1,求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/483f7e878a22a1591871dfcef3582a4c.png)
(2)如图2,
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/060705794ef87cc71dac40c57f27b1d2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e7d19f963f7c803bcfcbb265ec6d4304.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/50e8c257f5615d30660cef4157c6b273.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b871a762469393cdd22f15aa49ebb8f9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/be6a6301878fed2a01413020b27310a5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/50e8c257f5615d30660cef4157c6b273.png)
(3)如图3,
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d10b6175fb056760a9357936d14ffe82.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e3bb34308698b377df58ef5441aeec76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/daaff2c09eb9e6e35e7a29c7fd35dabd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7c4c7550e43c1bf7b1b685c38aa84a65.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0583bb491c76a8b6a5ec0fca652119c6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b4fc5fbc988d1c57e168cbc436230a79.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5096ed29dccc1e4df7f8b4494ce6d936.png)
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【推荐2】感知发现:(1)在学习平行线中,兴趣小组发现了很多有趣的模型图,如图1,当
时,可以得到结论:
.那么如果把条件和结论互换一下是否还成立呢?于是兴趣小组想尝试证明:如图1,
,求证:
.请写出证明过程.
(2)利用这个“模型结论”,我们可以解决很多问题.在综合与实践课上,同学们以“一个含
角的直角三角尺和两条平行线”为背景开展数学活动,如图2.已知两直线a,b且
和直角三角形
,
,
,
.创新小组的同学发现
,说明理由.
实践探究:
(3)如图3,
,在射线
是
的平分线,在
的延长线上取点N,连接
,若
,
,求
的度数.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b0fff774b4b0087a6f304ce930d359be.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dd6d9ef732deabacced5b48b2e32cf49.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dd6d9ef732deabacced5b48b2e32cf49.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b0fff774b4b0087a6f304ce930d359be.png)
(2)利用这个“模型结论”,我们可以解决很多问题.在综合与实践课上,同学们以“一个含
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3c030b25575d683af91c06e6a3e4f463.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d8a4352562ae8aa968014fd0d931b677.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/787ac5e13622afab5e9f8603afe42356.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1a3cc9cccfb4c260dac05f4ed57e8c10.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ab926d89b65f26c12e3da73ef1e5cf68.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e075468e7fb0bf30229aec01a7205977.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/87db26c93c31aa633abf8e57196c7a65.png)
实践探究:
(3)如图3,
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b0fff774b4b0087a6f304ce930d359be.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e42887d9bf31c1dd99f13c39e63c9ab9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/643e59176327bd52a66fbc507754b4b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83042953e7f15e984b2da2ee9ca678d1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a459f78e4a3516d8a8535290ede7f386.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1923b4daa138346838c2c77489c5a766.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2d4b59638c0838b664ff752a7c508814.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac2c42100dd2030e469a81d959a77b67.png)
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【推荐1】当已知三角形一边中点时,我们常通过“倍长中线”来构造全等的两个三角形,从而解决问题.
如图,已知
,点D是
的中点,延长
至点E,使
,连接
,易得到
,从而得到
,
.
已知
,点D是
的中点.
(1)如图1,点E在
上,延长
交
于点F,且
,求证:
;小明同学应用倍长中线的方法,延长
至点M,使
,连接
,请你帮助他写出证明过程.
(2)如图2,点E,G在射线
上,连接
,延长
交
于点F,若
,G为
的中点,求证:
;
(3)在(2)的条件下,若点M是线段
的中点,
,
垂直平分线段
,在
上有一动点P,连接
,当
的周长最小时,求
的度数.
如图,已知
![](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/03902478df1a55bc99703210bccab910.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0ad98ad714864041a632ca949308e417.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4eedae8d316c76e3d0b451256de03fb9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/decfd06ce63a98658db6f440ad7f8a5d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a5b59f0e6f7fa9c50e7f5cc146ba1af1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5d7fc2cd021ddef301baf6ccb2fc8e6a.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/8/1/9bc638a2-3a2c-450f-af1f-e486c5385b23.png?resizew=182)
已知
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/8/1/069e631b-d407-4db0-a40a-aa2b54e803d7.png?resizew=609)
(1)如图1,点E在
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.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/af8bfe298fb2948547723517cd2ec236.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a5b59f0e6f7fa9c50e7f5cc146ba1af1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/21037e170bdbb322558e79c40c00b454.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/da5710961e98c6811400da2c0b778d7b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e69d2b798744645af88a4fa411344a83.png)
(2)如图2,点E,G在射线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/67d822262ff00915910e5b87d81ad1ba.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ec45d10ee915662f63f9d3925d6ee539.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/abf80148409afb32ced0b4f59f1ba709.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/85c4bdfb0db1e31e8459df1d15f9ab55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3648fec702a9e60c7e577ff7f54405c3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/21037e170bdbb322558e79c40c00b454.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/82a6f7091bf0bb4b27a436d7cc29ca9d.png)
(3)在(2)的条件下,若点M是线段
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1e72b2e1ff83e95df048745322982451.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3e9a4522cde88082657e7119c7df3a1b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ff9d2abf13c2842f58654abf73c6b4ee.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/06e322e0c87479bba874db9ae9ba36b5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ff9d2abf13c2842f58654abf73c6b4ee.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/49fa1b7c7a71699e36794a14057a78b4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ffbb6763c631d9680525050c76218124.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b4257874d7910eb357589dc1954bdf76.png)
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【推荐2】在△ABC中,∠ABC=∠ACB,点D在直线BC上(不与B、C重合),点E在直线AC上(不与A、C重合),且∠ADE=∠AED.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/23/567eb488-8040-499e-bbe4-ea9e6533a4ca.png?resizew=472)
(1)如图1,若∠ABC=50°,∠AED=80°,则∠CDE= °,此时,
= .
(2)若点D在BC边上(点B、C除外)运动(如图1),试探究∠BAD与∠CDE的数量关系,并说明理由;
(3)若点D在线段BC的延长线上,点E在线段AC的延长线上(如图2),其余条件不变,请直接写出∠BAD与∠CDE的数量关系: .
(4)若点D在线段CB的延长线上(如图3),点E在直线AC上,∠BAD=26°,其余条件不变,则∠CDE= (友情提醒:可利用图3画图分析).
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/23/567eb488-8040-499e-bbe4-ea9e6533a4ca.png?resizew=472)
(1)如图1,若∠ABC=50°,∠AED=80°,则∠CDE= °,此时,
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d47b43a50e727de8e52ae2d9b58c6f3e.png)
(2)若点D在BC边上(点B、C除外)运动(如图1),试探究∠BAD与∠CDE的数量关系,并说明理由;
(3)若点D在线段BC的延长线上,点E在线段AC的延长线上(如图2),其余条件不变,请直接写出∠BAD与∠CDE的数量关系: .
(4)若点D在线段CB的延长线上(如图3),点E在直线AC上,∠BAD=26°,其余条件不变,则∠CDE= (友情提醒:可利用图3画图分析).
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