综合与实践——折纸中的数学.
我们在七年级上册第四章《几何图形初步》中探究了简单图形折叠问题,并进行了简单的计算与推理.七年级下册第五章学习了平行线的性质与判定后,我们进行了长方形纸条的折叠与平行线的探究,今天我们继续探究——折纸与平行线.
如图1,长方形纸条
中,
.第一步,将长方形纸条折叠,使折痕经过点
,得到折痕
,再将纸片展平;第二步,如图2,将折痕
折到
处,点
落在
处;第三步,如图3,将
对折,使点
落在
处,点
落在
处,
与
共线,得到折痕
.
![](https://img.xkw.com/dksih/QBM/2019/7/18/2249422655086592/2249700132470784/STEM/21312c6f4d19494bb1256d371bb48da5.png?resizew=194)
![](https://img.xkw.com/dksih/QBM/2019/7/18/2249422655086592/2249700132470784/STEM/a98a00f6789a435d9a906855a5f253cb.png?resizew=175)
(1)
和
有怎样的位置关系,并说明理由.
(2)折痕
和
有怎样的位置关系,并说明理由.
我们在七年级上册第四章《几何图形初步》中探究了简单图形折叠问题,并进行了简单的计算与推理.七年级下册第五章学习了平行线的性质与判定后,我们进行了长方形纸条的折叠与平行线的探究,今天我们继续探究——折纸与平行线.
如图1,长方形纸条
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a02b1139e07e431b5d4276757b232bad.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0ca6110d2cbe06f32f8481f8b50f8e38.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/68a83fdd2ba72a2dba0b6b10bb3e06b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3953cec61ac602ce5eb59b7912352179.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c41a8d86b80e8fbb222730eff0010e87.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1da895d8bd043625a0839128252130d9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/54a5d7d3b6b63fe5c24c3907b7a8eaa3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/28b1ba4307cfde9b424d468bfcdf6c5a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0bcf3c4e4663d3bfc82c826382b93c81.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/da650ee630c36fd5ce9abb4fb826df7b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/49b50357a6545cae8348e3059312f520.png)
![](https://img.xkw.com/dksih/QBM/2019/7/18/2249422655086592/2249700132470784/STEM/21312c6f4d19494bb1256d371bb48da5.png?resizew=194)
![](https://img.xkw.com/dksih/QBM/2019/7/18/2249422655086592/2249700132470784/STEM/a98a00f6789a435d9a906855a5f253cb.png?resizew=175)
(1)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e6e490f703eb6c9bb1278c78ebc2d661.png)
(2)折痕
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/49b50357a6545cae8348e3059312f520.png)
18-19七年级下·山西吕梁·期末 查看更多[3]
更新时间:2019-07-18 21:29:32
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解答题-证明题
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适中
(0.65)
【推荐1】完成下面推理过程:
如图,
和
交于点F,
,
,
.求证:
.
,
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又
( )
________(等量代换)
( )
________
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( )
如图,
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又
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又
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解答题-证明题
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适中
(0.65)
【推荐2】如图,∠1=∠2,∠3=∠D,∠4=∠5,运用平行线性质和判定证明:AE∥BF,要求写出具体的性质或判定定理.
![](https://img.xkw.com/dksih/QBM/2021/1/7/2631236100702208/2631674710130688/STEM/21c8983d80f6499a9aa4a6aa9df62a3d.png?resizew=161)
您最近一年使用:0次
解答题-证明题
|
适中
(0.65)
【推荐1】如图,已知矩形
的对角线
的垂直平分线与边
分别交于点
.
(1)求证:四边形
是菱形(请结合图①写出证明过程).
(2)如图②,矩形纸片
沿着
折叠,使得点
与点
重合,若
,试求
的长.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3cf9b288c48c73463a2f214f02b6952a.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/7/17/b0c00b38-80de-4dd2-8b06-3e54f91f455c.png?resizew=354)
(1)求证:四边形
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9766e5eb6796dafc5ffe212afdfc43c0.png)
(2)如图②,矩形纸片
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/49b50357a6545cae8348e3059312f520.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a88c6225ee65e6849aa0ddc62081101.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/49b50357a6545cae8348e3059312f520.png)
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解答题-证明题
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适中
(0.65)
【推荐2】如图1,将一张矩形纸片
沿着对角线
向上折叠,顶点
落到点
处,
交
于点
.
(1)求证:
是等腰三角形.
(2)如图2,过点
作
,交
于点
,连接
交
于点
.若
,
,求
的长.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d40b319212a7e7528b053e1c7097e966.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/85c4bdfb0db1e31e8459df1d15f9ab55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
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![](https://img.xkw.com/dksih/QBM/editorImg/2023/8/27/c92503ef-cffd-4fd4-8c43-389c84df3762.png?resizew=438)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d7e64c953aaf341e772a5fe776fbc78a.png)
(2)如图2,过点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f3da15d730c7fdaa9b6b4fe09a64a969.png)
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