如图,在
中,
,
,将
绕点A按顺时针旋转
得到
,连接
,它们交于D点,求证:
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/883fc5e3faf39829d60804b59deb1730.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3f81e24376a13d648c2ed0dc73bc710e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e170f206fdbbd834aad7580c727e2cc6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4c105d6ba18fbb0581fb982175e2eac9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5ec07ca71c03f8c1d6d3a1e2efcdff02.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f805768a5ffaf8bdfa4bc3b680aafdc9.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2024/4/3/c0e265e0-2f86-4b72-8305-b62e5fa1918e.png?resizew=159)
更新时间:2024-04-03 13:09:44
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相似题推荐
解答题-证明题
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【推荐1】数学课上老师要同学证明命题“对角线互相平分的四边形是平行四边形”是正确的.
小红同学先任意画出
,再取边
的中点O,连结
并延长到点D,使
,连结
,
(如图所示),并写出了如下尚不完整的已知和求证.
(1)补全已知和求证(在方框中填空).
(2)小红同学的思路是利用三角形全等,依据“一组对边平行且相等的四边形是平行四边形”来证明,请完成证明过程(可以用小红的思路,也可以用其他方法).
小红同学先任意画出
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/aaf1438142deeac876fc7dc50552e552.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5fce05f91ce17863abc8a5a8f6002b75.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
已知:如图,在四边形![]() ![]() ![]() 求证:四边形 ![]() | ![]() |
(2)小红同学的思路是利用三角形全等,依据“一组对边平行且相等的四边形是平行四边形”来证明,请完成证明过程(可以用小红的思路,也可以用其他方法).
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【推荐2】阅读课本材料,解答后面的问题.
折纸与证明
折纸,常常能为证明一个命题提供思路和方法.例如,在△ABC中,AB>AC(图27-1),怎样证明∠C>
∠B呢?
把AC沿∠A的平分线AD翻折,因为AB>AC,所以,点C落在AB上的点C’处(图27-2).于是,由∠AC’D>∠B,可得∠C>∠B.
在△ABC中,∠B=2∠C,点D为线段BC上一动点,当AD满足某种条件时,探讨在线段AB、BD、CD、AC四条线段中,某两条或某三条线段之间存在的数量关系.
(1)如图3,当AD⊥BC时,求证:AB+BD=DC;
![](https://img.xkw.com/dksih/QBM/2016/2/16/1573970567536640/1573970573426688/STEM/6b2d45b46a0c488d93d48ad857dfbcd2.png)
(2)如图4,当AD是∠BAC的角平分线时,写出AB、BD、AC的数量关系,并证明.
折纸与证明
折纸,常常能为证明一个命题提供思路和方法.例如,在△ABC中,AB>AC(图27-1),怎样证明∠C>
∠B呢?
把AC沿∠A的平分线AD翻折,因为AB>AC,所以,点C落在AB上的点C’处(图27-2).于是,由∠AC’D>∠B,可得∠C>∠B.
在△ABC中,∠B=2∠C,点D为线段BC上一动点,当AD满足某种条件时,探讨在线段AB、BD、CD、AC四条线段中,某两条或某三条线段之间存在的数量关系.
(1)如图3,当AD⊥BC时,求证:AB+BD=DC;
![](https://img.xkw.com/dksih/QBM/2016/2/16/1573970567536640/1573970573426688/STEM/6b2d45b46a0c488d93d48ad857dfbcd2.png)
(2)如图4,当AD是∠BAC的角平分线时,写出AB、BD、AC的数量关系,并证明.
![](https://img.xkw.com/dksih/QBM/2016/2/16/1573970567536640/1573970573426688/STEM/89b7ca6d63dc45049233e9ca0be1c309.png)
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【推荐1】(1)如图①所示,P是等边△ABC内的一点,连接PA、PB、PC,将△BAP绕B点顺时针旋转60°得△BCQ,连接PQ.若PA2+PB2=PC2,证明∠PQC=90°;
(2)如图②所示,P是等腰直角△ABC(∠ABC=90°)内的一点,连接PA、PB、PC,将△BAP绕B点顺时针旋转90°得△BCQ,连接PQ.当PA、PB、PC满足什么条件时,∠PQC=90°?请说明.
![](https://img.xkw.com/dksih/QBM/2019/6/17/2227560987770880/2228143983173632/STEM/f0e98ae84c854499818a99946aa614ae.png?resizew=163)
(2)如图②所示,P是等腰直角△ABC(∠ABC=90°)内的一点,连接PA、PB、PC,将△BAP绕B点顺时针旋转90°得△BCQ,连接PQ.当PA、PB、PC满足什么条件时,∠PQC=90°?请说明.
![](https://img.xkw.com/dksih/QBM/2019/6/17/2227560987770880/2228143983173632/STEM/f0e98ae84c854499818a99946aa614ae.png?resizew=163)
![](https://img.xkw.com/dksih/QBM/2019/6/17/2227560987770880/2228143983173632/STEM/b186f82bb4e9407eb99cfba556430278.png?resizew=146)
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解答题-问答题
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【推荐2】在平面直角坐标系
中,对于点
,点
和直线
,点
关于
的对称点为点
,点
是直线
上一点.将线段
绕点
逆时针旋转
得到
,如果线段
与直线
有交点,称点
是点
关于直线
和点
的“旋交点”.
,在点
,
,
中,是点A关于x轴和点B的“旋交点”的是 ;
(2)若点
的坐标是
,点
、
都在直线
上,点
是点
关于
轴和点
的“旋交点”,求点
的坐标;
(3)点
在以
为对角线交点,边长为2的正方形
(正方形的边与坐标轴平行)上,直线
,若正方形
上存在点
是点
关于直线
和点
的“旋交点”,直接写出
的取值范围.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7ee31829d0d4d5f779a957d7df8058ab.png)
![](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/0f85fca60a11e1af2bf50138d0e3fe62.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0f85fca60a11e1af2bf50138d0e3fe62.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e7c314398e26ffc7164b82946eeb4273.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0f85fca60a11e1af2bf50138d0e3fe62.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e663220a66eff19da6a71e46b397db2e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e7c314398e26ffc7164b82946eeb4273.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c02b54dc6b3e1bb6544f47d4c8743fcf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6eb97aff0960e2640314888a38e7169c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6eb97aff0960e2640314888a38e7169c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0f85fca60a11e1af2bf50138d0e3fe62.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0f85fca60a11e1af2bf50138d0e3fe62.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f77ba8b3cb02c27e2a207a27a5f77701.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1e1d45197f0d62d46cf211dfd6f26a8f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bc1fd831228679fd0df900dc84419f26.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/599b4cc0936acd0e29d7228dc2099a99.png)
(2)若点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9fa71aa2ea224669698850108751a71a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c31c4f39399ec245a67db2933ed639f2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d053b14c8588eee2acbbe44fc37a6886.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
(3)点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7b96dbf02194b5466bc11cb63c874c97.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0f85fca60a11e1af2bf50138d0e3fe62.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/36a1b09c653185842513e24ebba60bb3.png)
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