如图,在Rt△ABC中,∠ACB=90°,把Rt△ACB绕点B顺时针旋转得到Rt△BDE,连接CD并延长交AE于点F.
![](https://img.xkw.com/dksih/QBM/2022/4/23/2964503235551232/2967215176278016/STEM/afb273ce-b261-4fb0-8d7f-a5da9abd756b.png?resizew=317)
(1)求证:∠CBD=2∠EDF;
(2)若CD=EF,求∠BAC的度数.
![](https://img.xkw.com/dksih/QBM/2022/4/23/2964503235551232/2967215176278016/STEM/afb273ce-b261-4fb0-8d7f-a5da9abd756b.png?resizew=317)
(1)求证:∠CBD=2∠EDF;
(2)若CD=EF,求∠BAC的度数.
更新时间:2022-04-27 15:17:38
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相似题推荐
解答题-问答题
|
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名校
【推荐1】三折伞是我们生活中常用的一种伞,它的骨架是一个“移动副”和多个“转动副”组成的连杆机构,如图1是三折伞一条骨架的结构图,当“移动副”(标号1)沿着伞柄移动时,折伞的每条骨架都可以绕“转动副”(标号2-9)转动;图2是三折伞一条骨架的示意图,其中四边形
和四边形
都是平行四边形,
,
,
.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/4/3/e30cb8ca-09d3-4184-9602-06460d7e5a2c.png?resizew=416)
(1)若关闭折伞后,点
、
、
三点重合,点
与点
重合,求
的长度;
(2)在(1)的条件下,折伞完全撑开时,
,则点
到伞柄
距离为多少.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b32c05247f6998d7a70d31d13be4148c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0e27b886fd290425249e1f417a08e33d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/857f3b4f94bd62088a8bde74c16b81f5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e5b7612e40f22a9fa011683ac6531e7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/eee74f88bbae536862922630e4581fcf.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/4/3/e30cb8ca-09d3-4184-9602-06460d7e5a2c.png?resizew=416)
(1)若关闭折伞后,点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/73465a1f9aa03481295bf6bd3c6903ac.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7785afeeaf274892253d04b4f693b367.png)
(2)在(1)的条件下,折伞完全撑开时,
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/eb3f8cb648966fd4ff28896fe8f9e04d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/73465a1f9aa03481295bf6bd3c6903ac.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
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【推荐2】【教材呈现】下图是华师版八年级下册数学教材第121页的部分内容.
,将矩形纸片沿过点
的直线折叠,使点
落在边
上,点
的对应点为
,折痕为
,点
在
上.求证:四边形
是正方形.
【规律探索】(2)由【问题解决】可知,图①中的
为等腰三角形.现将图①中的点
沿
向右平移至点
处(点
在点
的左侧),如图②,折痕为
,点
在
上,点
在
上,那么
还是等腰三角形吗?请说明理由.
【结论应用】(3)在图②中,当
时,将矩形纸片继续折叠如图③,使点
与点
重合,折痕为
,点
在
上.要使四边形
为菱形,则
___________.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d83c15e14023ca74a365b685f363a87c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9e52a8f07834cbbbe4224962672fbbb2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e7c314398e26ffc7164b82946eeb4273.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e6e490f703eb6c9bb1278c78ebc2d661.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0054610b07c11f3cb88aa87b58c2df11.png)
【规律探索】(2)由【问题解决】可知,图①中的
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/791c9a8ecce70f679855ee110d446f8f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e7c314398e26ffc7164b82946eeb4273.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9e52a8f07834cbbbe4224962672fbbb2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/acc290b44635265137fdf13146b6a6d9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/acc290b44635265137fdf13146b6a6d9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4fb26d84907c923278ac4626a9d58947.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9e52a8f07834cbbbe4224962672fbbb2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e24d57917c6e6ab5b6e5421d308cc7ce.png)
【结论应用】(3)在图②中,当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bc5ce139702cc0eaf15022712510c394.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/55bb0405afa96ebf94c5b03fd52763dd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/895dc3dc3a6606ff487a4c4863e18509.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0ee1c8afa520493001a697f9842cd497.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c96e57c0595d832191594d11a1a0f15f.png)
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【推荐1】在
中,
,以
为斜边,作直角三角形
,
.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/11/30/fe09d4d1-6a71-49b8-a450-1d91b0fdfbcf.png?resizew=260)
(1)如图①,点
落在
内时,
,
,点
为
边的中点,
交
于
,求线段
的长;
(2)如图②,点
落在
外时,把
绕点
逆时针旋转一定角度,得到
,连接
交
于点
,点
在
上,且
.
①求证:
;
②求证:
是
的中点.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e428e7a09732be85c1224e9c8f6a71c5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6ab41054fa9ce51b68e78d9c0cf398d9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b79dd200766db27fb90d6bd1992cf658.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/10c6ee63b22008f64730404a63967d11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/68c54161819180b7b586a465c2032f7d.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/11/30/fe09d4d1-6a71-49b8-a450-1d91b0fdfbcf.png?resizew=260)
(1)如图①,点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e428e7a09732be85c1224e9c8f6a71c5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4752f7d6b1ad8678b83164092a10dc58.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e6ad473886193aeef7c539dd3c86ba04.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b79dd200766db27fb90d6bd1992cf658.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2d1cfa54ba2d5b8afa9b386d51ac632f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/764509115979e9958101808383672ec0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b3d9792485ccd1ba479ceba6397c15ff.png)
(2)如图②,点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e428e7a09732be85c1224e9c8f6a71c5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5bb961bd7db3adb76af2d4cedb611bd7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6a8b0d7e169313c2a2d5c278cf968b9a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8946331b0a9d86e1a9c78797f3021455.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/764509115979e9958101808383672ec0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1a6c6e7c025362c46a64a8956761f08e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1a7f1884593abfded963dda6ed3d95ed.png)
①求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/756260b6676f1f0f6459f14ac3c6309f.png)
②求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/764509115979e9958101808383672ec0.png)
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【推荐2】如图1,已知正方形
和正方形
,点E在
的延长线上,点G在边
上.
.
(2)现将正方形
绕点A按顺时针方向旋转
度
,在旋转过程中,探究下列问题.
①当正方形AEFG旋转至图2位置时,
分别交
,
于点M,N.求证:
.
②若
,
,当正方形
的顶点(点A除外)在直线
上时,求
的长度.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a8d0e8404f347a0eb4c76f4d25d9bdac.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/67d822262ff00915910e5b87d81ad1ba.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/29957564918bf2b8836bd6787a17c75c.png)
(2)现将正方形
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a8d0e8404f347a0eb4c76f4d25d9bdac.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e170f206fdbbd834aad7580c727e2cc6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/36a73dab03fbe220e272a20730ae7b0e.png)
①当正方形AEFG旋转至图2位置时,
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1e72b2e1ff83e95df048745322982451.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/85c4bdfb0db1e31e8459df1d15f9ab55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f7d573e81044852a4f024713f125deb7.png)
②若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/080ca48cd27d4bf9d9ef084b558fc17a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0afface6e34f75dc6fb982a423c08388.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a8d0e8404f347a0eb4c76f4d25d9bdac.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1e72b2e1ff83e95df048745322982451.png)
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【推荐1】如图,在
中,
是
的重心,
的延长线交边
于点
.
,使得
经过点B,且与
相切于点G;(不写作法,保留作图痕迹)
(2)在(1)的条件下,设
与半径
相交于点D,
交
于点E,连接
.若
,则弓形
的面积为______.(如需画草图,请使用图2)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/895dc3dc3a6606ff487a4c4863e18509.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/77a7e4a6765ce78b05ee97764771e01f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d97cdc586744d208b6f69c9813af977.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d97cdc586744d208b6f69c9813af977.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d50703c46b6153945d718b198f03b4b5.png)
(2)在(1)的条件下,设
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/307bd991211ec79b47a4be52933bb8e7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d97cdc586744d208b6f69c9813af977.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/91f3956f008cc29ca4bae44a087d5427.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/56e88b9320877fd308733e293d3946c8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/73cc4309dcef077fbcf60099f47b7b37.png)
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【推荐2】如图,
为
直径,
是
上一点,
于点
,弦
与
交于点
,过点
作
,使
,
交
的延长线于点
.过点
作
的切线交
的延长线于点
.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/3/16/78b1e0f3-32d2-47ac-ad26-85dc153f1832.png?resizew=138)
(1)求证:
是
的切线;
(2)若
,
,求弧AD的长;
(3)若
,
,求
的长.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d97cdc586744d208b6f69c9813af977.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d97cdc586744d208b6f69c9813af977.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f042c8513aa0d73ed6706f6ac1b36880.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e7d19f963f7c803bcfcbb265ec6d4304.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/50392644f1d0774a11e47e2e6a8db1b3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e6e490f703eb6c9bb1278c78ebc2d661.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d97cdc586744d208b6f69c9813af977.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/21037e170bdbb322558e79c40c00b454.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/895dc3dc3a6606ff487a4c4863e18509.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/3/16/78b1e0f3-32d2-47ac-ad26-85dc153f1832.png?resizew=138)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/91f3956f008cc29ca4bae44a087d5427.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d97cdc586744d208b6f69c9813af977.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9774f83067ed956a551bc41adcce0469.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a4931ea06ad9fd7abcac67e29bf8fadd.png)
(3)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ad5b71282cca19d04d44590645e6b30a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b7cbfaec1d9dcaaf159b060163436113.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/77a7e4a6765ce78b05ee97764771e01f.png)
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解答题-问答题
|
较难
(0.4)
【推荐1】在锐角
中,
,
,
,将
绕点
按逆时针方向旋转,得到
.
![](https://img.xkw.com/dksih/QBM/2021/1/25/2643645728407552/2652839060643840/STEM/423fea98-d10b-4d8d-8d2d-263942e82e93.png)
(1)当旋转成如图①,点
在线段
的延长线上时,则
的度数是________度;
(2)当旋转成如图②,连接
,
.若
的面积为4,求
的面积;
(3)点
为线段
的中点,点
是线段
上一动点,在
绕点
按逆时针方向旋转过程中,点
的对应点为点
,连接
,如图③,直接写出线段
长度的最大值和最小值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d2c15801fee2405573677484f5dcfa4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7788830ed1cb3b9c5988f70f43595f2e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b27e47690ed332c573186992b6d25654.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/abe4bdc5d9e833b23a1b916c06fc1a35.png)
![](https://img.xkw.com/dksih/QBM/2021/1/25/2643645728407552/2652839060643840/STEM/423fea98-d10b-4d8d-8d2d-263942e82e93.png)
(1)当旋转成如图①,点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9abaeba15f3abdd877bc701af52c5cd9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d8a71e8a816d9ef65d4bffd81fd53216.png)
(2)当旋转成如图②,连接
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4eedae8d316c76e3d0b451256de03fb9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ab2a2834d80ff574e79eae8ca8d4e94f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fd0c32d9f3badb7e51233dd39a39fbb3.png)
(3)点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cee6765a83140d745a6de4c85d9b6b50.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a5034016be10ad0c034f5d539c2b111a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a5034016be10ad0c034f5d539c2b111a.png)
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解答题-问答题
|
较难
(0.4)
【推荐2】综合与实践数学活动课上,张老师找来若干张等宽的矩形纸条,让学生们进行折纸探究.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/2/16/3ea233ce-bf72-4487-aa4f-7b7f149a71b6.png?resizew=163)
(1)希望小组将如图(1)所示的矩形纸片
沿过点
的直线折叠,使点
落在
边上的点
处,折痕为
.
埴空:图(1)中四边形
的形状是______.
(2)智慧小组准备了一张如图(2)所示的长、宽之比为
的矩形纸片
,用希望小组的方法折叠纸片,得到四边形
,接着沿过点
的直线折叠纸片,使点
落在
上的点
处,折痕为
,求
的度数.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/2/16/cd4cba0d-223f-4618-ba51-4178ae5d03ea.png?resizew=192)
(3)勤奋小组拿着一张如图(3)所示长为5,宽为2的矩形纸片
,利用希望小组的方法折叠纸片,得到四边形
,在
上取一点F(不与点
,
重合),沿
折叠
,点
的对应点为
,射线
交直线
于点
.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/2/16/d7fa1bbd-3976-49b1-a6f4-dbb30f82ade2.png?resizew=228)
①
与
的数量关系为______;
②当射线
经过
的直角边的中点时,直接写出
的长.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/2/16/3ea233ce-bf72-4487-aa4f-7b7f149a71b6.png?resizew=163)
(1)希望小组将如图(1)所示的矩形纸片
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5cb3f9a5da641be35117fd35ba07a6aa.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/764509115979e9958101808383672ec0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a18722354086c42e62334983fc50eb6a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d0213c5787a5a6b38d11bceca5567f67.png)
埴空:图(1)中四边形
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/687537f692080bdad116d82580fca710.png)
(2)智慧小组准备了一张如图(2)所示的长、宽之比为
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4dc4b1acbd1bb280989c86e801f424c5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5cb3f9a5da641be35117fd35ba07a6aa.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/687537f692080bdad116d82580fca710.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/69411c6c7c32c7907312923a0e0bfc1d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e8120f2eeb724c756b5f84a14c6df527.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/da783c3463e00e51f14179400646831f.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/2/16/cd4cba0d-223f-4618-ba51-4178ae5d03ea.png?resizew=192)
(3)勤奋小组拿着一张如图(3)所示长为5,宽为2的矩形纸片
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5cb3f9a5da641be35117fd35ba07a6aa.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/687537f692080bdad116d82580fca710.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8946331b0a9d86e1a9c78797f3021455.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e8120f2eeb724c756b5f84a14c6df527.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5df7626240940eb340420a605e95aeee.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0234cd0cb930b3179609d289c90e22cf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/764509115979e9958101808383672ec0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/54a829fdd8ec0f3b7ede883cf2c3e53b.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/2/16/d7fa1bbd-3976-49b1-a6f4-dbb30f82ade2.png?resizew=228)
①
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0faea42bc75978398093d8d2bf8d7f3a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/97f9242b4044051ad927fd4b5ab7a421.png)
②当射线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0234cd0cb930b3179609d289c90e22cf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/319e8d6b27b3b7f786deff5a68e19515.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/faee0268e5ede6318697e5a8509dd6f7.png)
您最近一年使用:0次
解答题-计算题
|
较难
(0.4)
真题
名校
【推荐3】筒车是我国古代利用水力驱动的灌溉工具,唐代陈廷章在《水轮赋》中写道:“水能利物,轮乃曲成”.如图,半径为
的筒车
按逆时针方向每分钟转
圈,筒车与水面分别交于点
、
,筒车的轴心
距离水面的高度
长为
,筒车上均匀分布着若干个盛水筒.若以某个盛水筒
刚浮出水面时开始计算时间.
首次到达最高点?
(2)浮出水面3.4秒后,盛水筒
距离水面多高?
(3)若接水槽
所在直线是
的切线,且与直线
交于点
,
.求盛水筒
从最高点开始,至少经过多长时间恰好在直线
上.(参考数据:
,
,
)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3a7f5caacb86858c7b0f1ea1de7bd227.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d97cdc586744d208b6f69c9813af977.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7c6c7567972273b4ba733b47bf9d5408.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/1dde8112e8eb968fd042418dd632759e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/828628c0876b45381c9a0edeb0fec236.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d66cc196a03b597cc17e5e99069a6329.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
(2)浮出水面3.4秒后,盛水筒
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
(3)若接水槽
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411461db15ee8086332c531e086c40c7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d97cdc586744d208b6f69c9813af977.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d923291b73773b7f90e4fabeb6c5689.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411461db15ee8086332c531e086c40c7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ed509457952856445283806f9091df0f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2d57dacbb8b5fc8f8128b7950ff5b516.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c0510ced3bd88288a0be8abf10895556.png)
您最近一年使用:0次