(1)如图1,在四边形
中,延长
、
交于点E,延长
、
交于点F.当
时,我们就称四边形
是“完美四边形”.已知在完美四边形
中,
.
①若
,则
______°;
②若
,则
的取值范围是______.
(2)在五边形中,延长任意不相邻的两边(如图2),在相交得到的角中,如果有四个角相等,我们就称这个五边形是“完美五边形”.
如图3,在五边形
中,
,
,该五边形是否为“完美五边形”?请说明你的理由.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7dea2ae9d515f9ab351ad72306b776ee.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d53c02fdb5baccf7c2480661a9657e0a.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/7013cc4303c7ac5d0f03c85423f0c258.png)
①若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6c96cb3ac8290e09c55d4eb336a8608.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/db90c0feb35aa54464f1303be9118f37.png)
②若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ced1d7f83074976d412251d7e3cdf108.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3981e7286d41960daf4e110c1c84e03a.png)
(2)在五边形中,延长任意不相邻的两边(如图2),在相交得到的角中,如果有四个角相等,我们就称这个五边形是“完美五边形”.
如图3,在五边形
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9142a8490de14a87eda628ffa7e28982.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/006402d0344baaf43cbc43868accea9c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8a11029ca6b4b9e7f777af0280cf163c.png)
22-23七年级下·江苏镇江·期末 查看更多[4]
江苏省镇江市2022-2023学年七年级下学期期末数学试题江苏省镇江市润州区镇江实验学校2022-2023学年七年级下学期期末数学试题(已下线)第11章 三角形(单元测试·拔尖卷)-2023-2024学年八年级数学上册基础知识专项突破讲与练(人教版)江苏省无锡市梁溪区侨谊实验中学2023-2024学年七年级下学期期中数学试题
更新时间:2023-07-20 20:47:47
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解答题-问答题
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【推荐1】操作:将一个含30°角的直角三角形放在一长方形纸片上,
(1)如图1所示,直角顶点P在长方形的边AB上,直角边交长方形的两边AD、BC于点E、F,如果图中的∠1=140°,那么∠2= 度.
(2)如图2所示,直角顶点P在长方形内,且长方形的顶点A、B在∠P的直角边上,那么图中的∠1与∠2会有怎样的关系?为什么?
(3)如果将30°角如图3摆放,使得长方形的顶点A、B在30°角的两边上,此时,你认为图中的∠1与∠2会有怎样的关系?请直接写出你的结论: .
(1)如图1所示,直角顶点P在长方形的边AB上,直角边交长方形的两边AD、BC于点E、F,如果图中的∠1=140°,那么∠2= 度.
(2)如图2所示,直角顶点P在长方形内,且长方形的顶点A、B在∠P的直角边上,那么图中的∠1与∠2会有怎样的关系?为什么?
(3)如果将30°角如图3摆放,使得长方形的顶点A、B在30°角的两边上,此时,你认为图中的∠1与∠2会有怎样的关系?请直接写出你的结论: .
![](https://img.xkw.com/dksih/QBM/2019/10/31/2323684901576704/2325054377836545/STEM/5992001980264d9c85efbf687d10c06d.png?resizew=542)
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【推荐2】补全解答过程:
(1)如图,线段AC=4,线段BC=9,点M是AC的中点,在CB上取一点N,CN:NB=1:2,求MN的长.
![](https://img.xkw.com/dksih/QBM/2020/2/13/2398071913275392/2398194964897792/STEM/a98b2a58305a4003b18320f8fcea4b71.png?resizew=212)
解:∵M是AC的中点,AC=4,
∴MC=
(填线段名称)= ,
又因为CN:NB=1:2,BC=9,
∴CN=
(填线段名称)= .
∴MN= (填线段名称)+ (填线段名称)=5.
∴MN的长为5.
(2)已知:如图,直线AB∥CD,直线EF与直线AB,CD分别交于点G,H;GM平分∠FGB,∠3=60°.求∠1的度数.
![](https://img.xkw.com/dksih/QBM/2020/2/13/2398071913275392/2398194964897792/STEM/4359c034acb74ecba8f4586f8c9ccf6e.png?resizew=187)
解:∵EF与CD交于点H,(已知)
∴∠3=∠4.( )
∵∠3=60°,( )
∴∠4=60°.
∵AB∥CD,EF与AB,CD交于点G,H,(已知)
∴∠4+∠FGB=180°.( )
∴∠FGB= .
∵GM平分∠FGB,(已知)
∴∠1= °.(角平分线的定义)
(1)如图,线段AC=4,线段BC=9,点M是AC的中点,在CB上取一点N,CN:NB=1:2,求MN的长.
![](https://img.xkw.com/dksih/QBM/2020/2/13/2398071913275392/2398194964897792/STEM/a98b2a58305a4003b18320f8fcea4b71.png?resizew=212)
解:∵M是AC的中点,AC=4,
∴MC=
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f89eef3148f2d4d09379767b4af69132.png)
又因为CN:NB=1:2,BC=9,
∴CN=
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4dac452fbb5ef6dd653e7fbbef639484.png)
∴MN= (填线段名称)+ (填线段名称)=5.
∴MN的长为5.
(2)已知:如图,直线AB∥CD,直线EF与直线AB,CD分别交于点G,H;GM平分∠FGB,∠3=60°.求∠1的度数.
![](https://img.xkw.com/dksih/QBM/2020/2/13/2398071913275392/2398194964897792/STEM/4359c034acb74ecba8f4586f8c9ccf6e.png?resizew=187)
解:∵EF与CD交于点H,(已知)
∴∠3=∠4.( )
∵∠3=60°,( )
∴∠4=60°.
∵AB∥CD,EF与AB,CD交于点G,H,(已知)
∴∠4+∠FGB=180°.( )
∴∠FGB= .
∵GM平分∠FGB,(已知)
∴∠1= °.(角平分线的定义)
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解答题-证明题
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较难
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【推荐1】如图,已知
与
互为补角,且
,
![](https://img.xkw.com/dksih/QBM/2020/2/4/2391863009116160/2392043430920192/STEM/f20a110dadbb4818a277833a31353935.png?resizew=166)
(1)求证:
;
(2)若
,
平分
,求证:
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d5b69d40b75d582c4b8ffa2369af1d41.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d57899ad4774aed9ccc7bd23db72153.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d1598ad60d36f87f7fed1a58cf5c2c42.png)
![](https://img.xkw.com/dksih/QBM/2020/2/4/2391863009116160/2392043430920192/STEM/f20a110dadbb4818a277833a31353935.png?resizew=166)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/39b12aa9d4f934868c3e4f51f73e7c89.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4b10134e7a46e6f6f7cb9d5e2371727d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4eedae8d316c76e3d0b451256de03fb9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8fabb884dc5f9609de491245463bbe9a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bb1150e7caf86393601b45976f94f3e5.png)
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【推荐2】在综合与实践课上,班级开展了以两条平行线和直角三角尺为主题的数学活动.
【初步感知】(1)如图1,若三角尺的
角的顶点G放在
上,若
,则
的度数为_________;
【自主探究】(2)将一副三角板如图2所示摆放,直线
.若三角板
不动,而三角板
绕点D以每秒
的速度顺时针旋转,设旋转时间为t秒
,求当旋转到
时,
的值是多少?
【探究拓展】(3)现将三角板
绕点A以每秒
的速度顺时针旋转,同时三角板
绕点D以每秒
的速度顺时针旋转,如图3,设时间为t秒,当
时,若边
与三角板
的一条直角边(边
)平行,求出所有满足条件的
值.(请直接写出满足条件的
值)
【初步感知】(1)如图1,若三角尺的
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d5b69d40b75d582c4b8ffa2369af1d41.png)
【自主探究】(2)将一副三角板如图2所示摆放,直线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1c8be88ce325838b79a377e026a437ea.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/134ef0b1a2669a09f05bd4dc2496f706.png)
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【探究拓展】(3)现将三角板
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【推荐1】定义:一组邻边相等且对角互补的四边形叫做“等补四边形”
如图1,四边形ABCD中,AD=CD,∠A+∠C=180°,则四边形ABCD叫做“等补四边形”.
(1)概念理解
①在以下四种图形中,一定是“等补四边形”的是( )
A.平行四边形 B.菱形 C.矩形 D.正方形
②等补四边形ABCD中,若∠B∶∠C∶∠D=2∶3∶4,则∠A= ;
(2)知识运用
如图1,在四边形ABCD中,BD平分∠ABC,AD=CD,BC>BA.求证:四边形ABCD是等补四边形
(3)探究发现
如图2,在等补四边形ABCD中,AB=AD,连接AC,AC是否平分∠BCD?请说明理由.
如图1,四边形ABCD中,AD=CD,∠A+∠C=180°,则四边形ABCD叫做“等补四边形”.
(1)概念理解
①在以下四种图形中,一定是“等补四边形”的是( )
A.平行四边形 B.菱形 C.矩形 D.正方形
②等补四边形ABCD中,若∠B∶∠C∶∠D=2∶3∶4,则∠A= ;
(2)知识运用
如图1,在四边形ABCD中,BD平分∠ABC,AD=CD,BC>BA.求证:四边形ABCD是等补四边形
(3)探究发现
如图2,在等补四边形ABCD中,AB=AD,连接AC,AC是否平分∠BCD?请说明理由.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/18/d2fa503f-3021-44a1-95e3-abeafbdd7bdf.png?resizew=285)
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【推荐2】已知,
中,
.
![](https://img.xkw.com/dksih/QBM/editorImg/2024/3/15/93320c80-b02e-4cb5-aa2b-eebb73d5ae4d.png?resizew=455)
(1)如图1,求证:
;
(2)如图2,
是
外一点,连接
、
,且
,作
的平分线交
于点
,若
,求
的度数;
(3)如图3,在(2)的条件下,连接
交
于点
,若
,
,求
的长.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9bac9527bdbb49d1b213a0ff67e3da95.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2024/3/15/93320c80-b02e-4cb5-aa2b-eebb73d5ae4d.png?resizew=455)
(1)如图1,求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/047dc9795efa99b6fb9fdf9778085dab.png)
(2)如图2,
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d40b319212a7e7528b053e1c7097e966.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2e735a28578ba191da6d4f3b0f8e8729.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5157b42da58d55daad27d98b2fec15ff.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/b57fdd2a3642716fcf5100011eb3ec88.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7cd1bc0388e7fad3e849ca39c67f5034.png)
(3)如图3,在(2)的条件下,连接
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/68a83fdd2ba72a2dba0b6b10bb3e06b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bbc39144b305c67d44410d41053a1d28.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/50f218914337edd06e59e75d90b777e6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e6e490f703eb6c9bb1278c78ebc2d661.png)
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