定义:有一组对角相等而另一组对角不相等的凸四边形叫做“等对角四边形”.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/9/25/b18a911b-9ff7-40d3-a47a-68d5b99805ee.png?resizew=291)
(1)如图1,四边形ABCD是“等对角四边形”,∠B≠∠D,∠B=90°,∠D=105°,则∠C=______°;
(2)已知,在△ABC中,AC=4,BC=3,AB=5,D为AC的中点,E是线段AB上一点,当四边形BCDE是“等对角四边形”时.求对角线CE的长;
(3)如图2,在平面直角坐标系xOy中,四边形ABCD为“等对角四边形”,其顶点A,C的坐标分别为(﹣
,0),(
,0),顶点B在y轴上,顶点D在第四象限内,且∠ADC=120°.P为坐标平面内的一点,抛物线y=ax2+bx+c(a>0)过A,C,P三点,当满足∠APC=
∠ADC的P点至少有3个时,请直接写出a的取值范围.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/9/25/b18a911b-9ff7-40d3-a47a-68d5b99805ee.png?resizew=291)
(1)如图1,四边形ABCD是“等对角四边形”,∠B≠∠D,∠B=90°,∠D=105°,则∠C=______°;
(2)已知,在△ABC中,AC=4,BC=3,AB=5,D为AC的中点,E是线段AB上一点,当四边形BCDE是“等对角四边形”时.求对角线CE的长;
(3)如图2,在平面直角坐标系xOy中,四边形ABCD为“等对角四边形”,其顶点A,C的坐标分别为(﹣
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a7ffe8515ff6183c1c7775dc6f94bdb8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a7ffe8515ff6183c1c7775dc6f94bdb8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f89eef3148f2d4d09379767b4af69132.png)
更新时间:2022-04-18 22:09:30
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【推荐1】已知抛物线
与x轴交于A,B两点(点A在点B的左侧).
(1)若该抛物线的对称轴为直线
.
①求该抛物线的解析式;
②在对称轴上是否存在一点P,使点B关于直线
的对称点
恰好落在对称轴上.若存在,请求出点P的坐标;若不存在,请说明理由.
(2)当
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(1)若该抛物线的对称轴为直线
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①求该抛物线的解析式;
②在对称轴上是否存在一点P,使点B关于直线
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(2)当
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【推荐2】如图所示,线段
,
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,
,点
为射线
上一点,
平分
交线段
于点
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重合).
![](https://img.xkw.com/dksih/QBM/2020/2/4/2391631109775360/2391684272914432/STEM/1ccacdb21f9d4efd9850bde891441690.png?resizew=399)
(1)当
为锐角,且
时,求四边形
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与
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(3)设
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(1)当
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(2)当
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解答题-作图题
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【推荐1】如图1,在长方形
中,
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边的中点时,
________;
(2)连接
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,当
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解答题-问答题
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名校
【推荐2】如图,在矩形
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(2)如图2,连接
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【推荐1】如图,一个三角形的纸片ABC,其中∠A=∠C,∠B=118°.
(1)把△ABC纸片按图1所示折叠,使点A落在AC边上的点F处,DE是折痕,说明BC∥DF;
(2)把△ABC纸片沿DE折叠,当点A落在四边形BCED内时(如图2),探索∠C与∠1+∠2之间的数量关系,并说明理由;
(3)当点A落在四边形BCED外时(如图3),若∠1=29°,则∠2= °.(直接写出结论).
(1)把△ABC纸片按图1所示折叠,使点A落在AC边上的点F处,DE是折痕,说明BC∥DF;
(2)把△ABC纸片沿DE折叠,当点A落在四边形BCED内时(如图2),探索∠C与∠1+∠2之间的数量关系,并说明理由;
(3)当点A落在四边形BCED外时(如图3),若∠1=29°,则∠2= °.(直接写出结论).
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/21/f6ec673b-073e-47e8-b343-b99593cb9b08.png?resizew=620)
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【推荐2】如图1,在四边形ABCD中,AB=AC,∠BAC=60°,∠B+∠C+∠ADB=4∠BAC,
![](https://img.xkw.com/dksih/QBM/editorImg/2022/9/19/c26dae76-90e8-401f-8929-f4849945f157.png?resizew=360)
(1)求∠ADC的度数;
(2)如图2,若AD=BD+CD,求证:AD平分∠BDC;
(3)如图3,在(2)的条件下,E、F分别在AC、AB上,交于点P,使得∠BPC=∠BDC,若BD=EF=7,AD=15,求△EFP的⾯积.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/9/19/c26dae76-90e8-401f-8929-f4849945f157.png?resizew=360)
(1)求∠ADC的度数;
(2)如图2,若AD=BD+CD,求证:AD平分∠BDC;
(3)如图3,在(2)的条件下,E、F分别在AC、AB上,交于点P,使得∠BPC=∠BDC,若BD=EF=7,AD=15,求△EFP的⾯积.
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【推荐2】已知
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