(本小题满分8分)
如图,在
中,
.将
绕点
按逆时针方向旋转后得
,
、
相交于点
,连接
.当
时,求
的度数.
如图,在
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/37532f4eb60ed8b3fac74cb612e25699.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a25c28359f8d8da9eaf4672a6cf8ae4f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e6e490f703eb6c9bb1278c78ebc2d661.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7d97dc3b752832906de41447bb58a341.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d55e1b9d14696722d3e3364e9d7f4b1e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e35cfb01d9e4729e9b41eb33feb5b8c6.png)
![](https://img.xkw.com/dksih/QBM/2020/8/6/2521860608852992/2522113096081408/STEM/d498e7e2140d4b00a401043a937f5fab.png?resizew=195)
更新时间:2020-08-06 18:35:08
|
相似题推荐
解答题-证明题
|
适中
(0.65)
【推荐1】如图,在
中,
,垂足为D点E在BC上,
,垂足为F,
.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/13/8426d7d0-d1dc-4940-8e36-78c5abebfc81.png?resizew=207)
(1)试说明
的理由;
(2)如果
,且
,求
的度数.
解:(1)填空证明:∵
,![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ab00e0cff0876c4183a47f1272cf9928.png)
∴
________
∴
________(_________________)
又∵
.
∴
________
∴
(_________________)
(2)解答过程写在答题卡上
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8b757f0c42ae5c9a2d6a4b19e5877b27.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ab00e0cff0876c4183a47f1272cf9928.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0e53497af8899cb299d762f1a4f46a55.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/13/8426d7d0-d1dc-4940-8e36-78c5abebfc81.png?resizew=207)
(1)试说明
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f49da919805f7e02e7e8f5bcfd8a9d29.png)
(2)如果
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e96337c944f933c3b51f5184c789a379.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1c42e0153bc0cc5b537e8b733740c069.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/605f2976297a0deaa1602ef09d6a5afa.png)
解:(1)填空证明:∵
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8b757f0c42ae5c9a2d6a4b19e5877b27.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ab00e0cff0876c4183a47f1272cf9928.png)
∴
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/06222ee533c2484ab25321a6abbf98cb.png)
∴
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/207c37b4e9eb8c53fd2ae13c7afe92dc.png)
又∵
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0e53497af8899cb299d762f1a4f46a55.png)
∴
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1503237215798ab4694f90a3a5390787.png)
∴
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f49da919805f7e02e7e8f5bcfd8a9d29.png)
(2)解答过程写在答题卡上
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解答题-证明题
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适中
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【推荐2】如图,在
和
中,点
在
边上,
,
,
,
与
交于点
.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/7/23/a232d069-9383-4e0e-8303-f6602bc0497a.png?resizew=316)
(1)求证:
;
(2)若
,
,求
的度数.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4c105d6ba18fbb0581fb982175e2eac9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/be5fc6ead6416492c231c320a5486f86.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/49cb6392b1f859954303066037c5f5fd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9c2b3d993a79210952ef190542700111.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/49b50357a6545cae8348e3059312f520.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/895dc3dc3a6606ff487a4c4863e18509.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/7/23/a232d069-9383-4e0e-8303-f6602bc0497a.png?resizew=316)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d7dab0c0c0f988903f228a6510208420.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/38aeb5da81832455ab5fd4437b554c3a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dbefe891b848d6aa86f256628a4a4a6c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/600f68bbb24b2f34b6f5ebca90939535.png)
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解答题-证明题
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适中
(0.65)
【推荐1】如图1,△ABC是边长为4cm的等边三角形,边AB在射线OM上,且OA=6cm.点D从O点出发,沿OM的方向以1cm/s的速度运动.当D不与点A重合时,将△ACD绕点C逆时针方向旋转60°得到△BCE,连接DE.
(1)如图1,求证:△CDE是等边三角形;
(2)如图1,设D点的运动时间为ts,当t为多少时,∠DCB=90°;
(3)如图2,设D点的运动时间为ts,当6<t<10时,△BDE的周长是否存在最小值?若存在,求出△BDE的最小周长;若不存在,说明理由.
(1)如图1,求证:△CDE是等边三角形;
(2)如图1,设D点的运动时间为ts,当t为多少时,∠DCB=90°;
(3)如图2,设D点的运动时间为ts,当6<t<10时,△BDE的周长是否存在最小值?若存在,求出△BDE的最小周长;若不存在,说明理由.
![](https://img.xkw.com/dksih/QBM/editorImg/2024/6/13/507822f1-388f-40d1-a971-dbd94be95b92.png?resizew=361)
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名校
【推荐2】如图,把一直角三角尺ACB绕30°角的顶点B顺时针旋转,使点A与CB的延长线上的点E重合,连接CD.
![](https://img.xkw.com/dksih/QBM/2017/7/12/1728649892610048/1730644261986304/STEM/03d4091a40c948d08b45a28812ea4c08.png?resizew=247)
(1)三角尺旋转了多少度?试判断△CBD的形状;
(2)若∠BCD=15°,求∠CDE的度数.
![](https://img.xkw.com/dksih/QBM/2017/7/12/1728649892610048/1730644261986304/STEM/03d4091a40c948d08b45a28812ea4c08.png?resizew=247)
(1)三角尺旋转了多少度?试判断△CBD的形状;
(2)若∠BCD=15°,求∠CDE的度数.
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解答题-证明题
|
适中
(0.65)
【推荐1】如图,四边形
中,
,连接对角线
,
,点
在
上,将
绕点
顺时针旋转
得到
,且点
在
上.
(1)求证:
;
(2)若
,求证:四边形
是菱形.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/13285b89cefa3dbe140ee32bff9b5621.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f0d801edd85c816522ae1e40b83ae9ba.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4b10134e7a46e6f6f7cb9d5e2371727d.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/4eedae8d316c76e3d0b451256de03fb9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/260200d547998bcac50a4a491382e7f4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4cae70b8a9d2d2e96dea62c00ced04b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e444739e269a94733b2b0598b559313.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6ff56ea00ca90825f3d95809de24f639.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/3/17/3dc2bf4e-d58a-4501-b5f6-eab26dbdaa0a.png?resizew=177)
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解答题-问答题
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【推荐2】综合与实践
问题情境:
数学活动课上,同学们将
绕点A顺时针旋转得到
,点
落在边AB上,连接
,过点
作
于点D.
特例分析:
(1)如图1,若点D与点A重合,请判断线段AC与BC之间的数量关系,并说明理由;
探索发现:
(2)如图2,若点D在线段CA的延长线上.且
,请判断线段AD与
之间的数量关系,并说明理由.
问题情境:
数学活动课上,同学们将
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83e45834cc338a0a05e83ded41639630.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8d2065fe85fc583dd9b587a0933f003d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b4c8a9c4957431681ddfc77895a88508.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6655cc150ddc9deba2254780984d0024.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3953cec61ac602ce5eb59b7912352179.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ec2712dd0be9d21e43720b3c4c1895da.png)
特例分析:
(1)如图1,若点D与点A重合,请判断线段AC与BC之间的数量关系,并说明理由;
探索发现:
(2)如图2,若点D在线段CA的延长线上.且
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3cc256443dbb780b9d8846eb19408740.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e0f0ccc8492a0ccf1eee24867060643.png)
![](https://img.xkw.com/dksih/QBM/2022/1/13/2893758724227072/2895875997212672/STEM/e862a9ad-86bb-48c4-aea5-179825555712.png?resizew=306)
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