我们定义:有一组邻边相等且有一组对角互补的凸四边形叫做等补四边形
(1)概念理解
①根据上述定义举一个等补四边形的例子:
②如图1,四边形ABCD中,对角线BD平分∠ABC,∠A+∠C=180°,求证:四边形ABCD是等补四边形
(2)性质探究:
③小明在探究时发现,由于等补四边形有一组对角互补,可得等补四边形的四个顶点共圆,如图2,等补四边形ABCD内接于⊙O,AB=AD,则∠ACD ∠ACB(填“>”“<”或“=“);
④若将两条相等的邻边叫做等补四边形的“等边”,等边所夹的角叫做“等边角”,它所对的角叫做“等边补角”连接它们顶点的对角线叫做“等补对角线”,请用语言表述③中结论:
(3)问题解决
在等补四边形ABCD中,AB=BC=2,等边角∠ABC=120°,等补对角线BD与等边垂直,求CD的长.
(1)概念理解
①根据上述定义举一个等补四边形的例子:
②如图1,四边形ABCD中,对角线BD平分∠ABC,∠A+∠C=180°,求证:四边形ABCD是等补四边形
(2)性质探究:
③小明在探究时发现,由于等补四边形有一组对角互补,可得等补四边形的四个顶点共圆,如图2,等补四边形ABCD内接于⊙O,AB=AD,则∠ACD ∠ACB(填“>”“<”或“=“);
④若将两条相等的邻边叫做等补四边形的“等边”,等边所夹的角叫做“等边角”,它所对的角叫做“等边补角”连接它们顶点的对角线叫做“等补对角线”,请用语言表述③中结论:
(3)问题解决
在等补四边形ABCD中,AB=BC=2,等边角∠ABC=120°,等补对角线BD与等边垂直,求CD的长.
![](https://img.xkw.com/dksih/QBM/2020/4/13/2440405465800704/2440607807135744/STEM/5c34038337474e0faad9bcf1a4089feb.png?resizew=299)
更新时间:2020-04-13 14:52:12
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解答题-证明题
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较难
(0.4)
【推荐1】已知四边形
是菱形,
,
,
的两边分别与射线
,
相交于点E,
,且
.
(1)如图1,当点
是线段
的中点时,直接写出线段
,
之间的数量关系;
![](https://img.xkw.com/dksih/QBM/2020/11/14/2592745039396864/2596972586139648/STEM/5a07e4b1-2dc0-428c-892a-ee43b04be4ff.png?resizew=271)
(2)如图2,当点
是线段
上任意一点时(点
不与
,
重合),求证:
;
![](https://img.xkw.com/dksih/QBM/2020/11/14/2592745039396864/2596972586139648/STEM/9da0c52a-8098-417f-9966-55ced230bc3f.png?resizew=226)
(3)如图3,当点
在线段
的延长线上,且
时,求
的面积.
![](https://img.xkw.com/dksih/QBM/2020/11/14/2592745039396864/2596972586139648/STEM/f7325b6e-5d4c-4e81-9f37-dc4bf6d746fd.png?resizew=257)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d2c15801fee2405573677484f5dcfa4.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4a9eb456c912e01458c19b06e83a5c9d.png)
(1)如图1,当点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6b1bd1adfe4cc6566218f19970c2fd3b.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6aa2b5e09f8ec785c59900a529390a02.png)
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(2)如图2,当点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6b1bd1adfe4cc6566218f19970c2fd3b.png)
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(3)如图3,当点
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6b1bd1adfe4cc6566218f19970c2fd3b.png)
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【推荐2】如图,平面直角坐标系中,点
,
,
,
,
.
解析式;
(2)点
在直线
上,
,直接写出点
的坐标
__________;
(3)
是平面内一点,若
与
全等,则点
坐标为___________.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6f943121691740928470268b34781e06.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d2b34233772c4c26d6669499d9b1f15a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a6b41d4070854edfaa24071137b314cb.png)
(2)点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a6b41d4070854edfaa24071137b314cb.png)
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(3)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
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解题方法
【推荐1】如图1,在△ABC中,AB=AC=2,∠BAC=90°,点P为BC边的中点,直线a经过点A,过B作BE⊥a,垂足为E,过C作CF⊥a,垂足为F,连接PE、PF.
(1)当点B、P在直线a的异侧时,延长EP交CF于点G,猜想线段PF和EG的数量关系为_____;
(2)如图2,直线a绕点A旋转,当点BP在直线a的同侧时,若(1)中其它条件不变,(1)中的结论还成立吗?若成立,请给予证明;若不成立,请说明理由;
(3)直线a绕点A旋转一周的过程中,当线段PF的长度最大时,请判断四边形BEFC的形状,并求出它的面积.
(1)当点B、P在直线a的异侧时,延长EP交CF于点G,猜想线段PF和EG的数量关系为_____;
(2)如图2,直线a绕点A旋转,当点BP在直线a的同侧时,若(1)中其它条件不变,(1)中的结论还成立吗?若成立,请给予证明;若不成立,请说明理由;
(3)直线a绕点A旋转一周的过程中,当线段PF的长度最大时,请判断四边形BEFC的形状,并求出它的面积.
![](https://img.xkw.com/dksih/QBM/2021/5/16/2722105339551744/2722309684740096/STEM/49354b0b-6a2a-444a-a561-45fe04a5f5a7.png)
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【推荐2】如图1,在菱形
中,
,
,点
,
分别在
,
上,且
,
,连接
,
.
![](https://img.xkw.com/dksih/QBM/2022/4/1/2953818614767616/2964181297324032/STEM/d1910eab-d16b-42fa-bc8f-3cca122904fa.png?resizew=591)
(1)请直接写出
的值_______;
(2)连接
.将
绕点
逆时针旋转到图2的位置,求
的值,并说明理由;
(3)在
绕点
旋转的过程中,当
,
,
三点共线时,请直接写出线段
的长.
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(1)请直接写出
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(2)连接
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(3)在
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4cae70b8a9d2d2e96dea62c00ced04b9.png)
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解答题-问答题
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【推荐1】在矩形
中,点E是
边上一动点,连接
,过点B作
于点G,交
边于点F.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/1/16/1b899664-3ead-41ef-bdac-aabb1dbad7d2.png?resizew=358)
(1)当矩形
是正方形时,以点F为直角顶点在正方形
的外部作等腰直角三角形
,连接
.请直接写出
与
之间的数量关系.
(2)如图2,
,
,以
和
为邻边作平行四边形
,请探究线段
与
之间数量关系,并说明理由.
(3)在(2)的条件下即
,
,若M是
的中点,连接
,求
的最小值.
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(1)当矩形
![](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/630a21ba7a8e1b8bca73c1634cc6f74d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/589786dd7c3a2679c3230b671cd232d6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/68a83fdd2ba72a2dba0b6b10bb3e06b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/589786dd7c3a2679c3230b671cd232d6.png)
(2)如图2,
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/efc6e4b936d7a800e839a30c3839574d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ef0402dd5ae3db10281f9f1e11738bcb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/85c4bdfb0db1e31e8459df1d15f9ab55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/274cf35acb4a1748d15c39d15a9bea7b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b2746836e6b83bc9462db060d6b72d43.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/68a83fdd2ba72a2dba0b6b10bb3e06b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/589786dd7c3a2679c3230b671cd232d6.png)
(3)在(2)的条件下即
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/efc6e4b936d7a800e839a30c3839574d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ef0402dd5ae3db10281f9f1e11738bcb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/49b50357a6545cae8348e3059312f520.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8e9e953a4a5f98c96bbe67cbaadf76d9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8e9e953a4a5f98c96bbe67cbaadf76d9.png)
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【推荐2】在平面直角坐标系中,A(0,a)、B(﹣b,0),若b=
+4,C点是B点关于y轴的对称点.
(1)判断△ABC的形状并证明;
(2)P点在第一象限,且∠APC=135°,试探究关于PA、PB、PC三条线段的确定数量关系;
(3)E点在BC上,F为线段AE的中点,EF绕E点顺时针旋转60°得到EG,E点从B点沿BC运动到C点,求G点随E点运动的路径长.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e499e979ec91b9815d5181dfa591c7b4.png)
(1)判断△ABC的形状并证明;
(2)P点在第一象限,且∠APC=135°,试探究关于PA、PB、PC三条线段的确定数量关系;
(3)E点在BC上,F为线段AE的中点,EF绕E点顺时针旋转60°得到EG,E点从B点沿BC运动到C点,求G点随E点运动的路径长.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/6/24/1ade0759-1973-494b-a664-0bba710df0f7.png?resizew=313)
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名校
【推荐3】问题提出:
平面内不在同一条直线上的三点确定一个圆.那么平面内的四点(任意三点均不在同一直线上),能否在同一个圆呢?
初步思考
设不在同一条直线上的三点A、B、C确定的圆为⊙O.
(1)当C、D在线段AB的同侧时,
如图①,若点D在⊙O上,此时有∠ACB=∠ADB,理由是 ;
如图②,若点D在⊙O内,此时有∠ACB ∠ADB;
如图③,若点D在⊙O外,此时有∠ACB ∠ADB.(填“=”、“>”或“<”);
![](https://img.xkw.com/dksih/QBM/2015/6/4/1573845897945088/1573845903777792/STEM/81b43336-be3a-45ab-abc9-b85cac0c3b07.png?resizew=569)
由上面的探究,请直接写出A、B、C、D四点在同一个圆上的条件: .
类比学习
(2)仿照上面的探究思路,请探究:当C、D在线段AB的异侧时的情形.
![](https://img.xkw.com/dksih/QBM/2015/6/4/1573845897945088/1573845903777792/STEM/0605ed1e-209c-4041-9fd1-7a764bf91dd4.png?resizew=148)
![](https://img.xkw.com/dksih/QBM/2015/6/4/1573845897945088/1573845903777792/STEM/7ec9aed4-bdd4-494c-aa82-0e554d919d44.png?resizew=152)
![](https://img.xkw.com/dksih/QBM/2015/6/4/1573845897945088/1573845903777792/STEM/a4ac62a3-3e63-4490-ba5e-c31be761dd6b.png?resizew=154)
此时有 , 此时有 , 此时有 .
由上面的探究,请用文字语言直接写出A、B、C、D四点在同一个圆上的条件: .
拓展延伸
(3)如何过圆上一点,仅用没有刻度的直尺,作出已知直径的垂线?
已知:如图,AB是⊙O的直径,点C在⊙O上.
求作:CN⊥AB.
作法:①连接CA,CB;
②在上任取异于B、C的一点D,连接DA,DB;
③DA与CB相交于E点,延长AC、BD,交于F点;
④连接F、E并延长,交直径AB于M;
⑤连接D、M并延长,交⊙O于N.连接CN.
则CN⊥AB.
请按上述作法在图④中作图,并说明CN⊥AB的理由.(提示:可以利用(2)中的结论)
平面内不在同一条直线上的三点确定一个圆.那么平面内的四点(任意三点均不在同一直线上),能否在同一个圆呢?
初步思考
设不在同一条直线上的三点A、B、C确定的圆为⊙O.
(1)当C、D在线段AB的同侧时,
如图①,若点D在⊙O上,此时有∠ACB=∠ADB,理由是 ;
如图②,若点D在⊙O内,此时有∠ACB ∠ADB;
如图③,若点D在⊙O外,此时有∠ACB ∠ADB.(填“=”、“>”或“<”);
![](https://img.xkw.com/dksih/QBM/2015/6/4/1573845897945088/1573845903777792/STEM/81b43336-be3a-45ab-abc9-b85cac0c3b07.png?resizew=569)
由上面的探究,请直接写出A、B、C、D四点在同一个圆上的条件: .
类比学习
(2)仿照上面的探究思路,请探究:当C、D在线段AB的异侧时的情形.
![](https://img.xkw.com/dksih/QBM/2015/6/4/1573845897945088/1573845903777792/STEM/0605ed1e-209c-4041-9fd1-7a764bf91dd4.png?resizew=148)
![](https://img.xkw.com/dksih/QBM/2015/6/4/1573845897945088/1573845903777792/STEM/7ec9aed4-bdd4-494c-aa82-0e554d919d44.png?resizew=152)
![](https://img.xkw.com/dksih/QBM/2015/6/4/1573845897945088/1573845903777792/STEM/a4ac62a3-3e63-4490-ba5e-c31be761dd6b.png?resizew=154)
此时有 , 此时有 , 此时有 .
由上面的探究,请用文字语言直接写出A、B、C、D四点在同一个圆上的条件: .
拓展延伸
(3)如何过圆上一点,仅用没有刻度的直尺,作出已知直径的垂线?
已知:如图,AB是⊙O的直径,点C在⊙O上.
求作:CN⊥AB.
作法:①连接CA,CB;
②在上任取异于B、C的一点D,连接DA,DB;
③DA与CB相交于E点,延长AC、BD,交于F点;
④连接F、E并延长,交直径AB于M;
⑤连接D、M并延长,交⊙O于N.连接CN.
则CN⊥AB.
请按上述作法在图④中作图,并说明CN⊥AB的理由.(提示:可以利用(2)中的结论)
![](https://img.xkw.com/dksih/QBM/2015/6/4/1573845897945088/1573845903777792/STEM/2415cd6f-a191-4755-9a5f-638fba2e70ba.png?resizew=184)
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