填空完成推理过程:
如图,点E在AB上,点F在CD上,∠1=∠2,∠B=∠C,求证AB∥CD.
证明:∵∠1=∠2(已知),
∠1=∠4( ),
∴∠2=∠4( ),
∴EC∥BF( )
∴∠3= ( ),
又∵∠B=∠C( ),
∴∠3=∠B( ),
∴AB∥CD( ).
如图,点E在AB上,点F在CD上,∠1=∠2,∠B=∠C,求证AB∥CD.
证明:∵∠1=∠2(已知),
∠1=∠4( ),
∴∠2=∠4( ),
∴EC∥BF( )
∴∠3= ( ),
又∵∠B=∠C( ),
∴∠3=∠B( ),
∴AB∥CD( ).
![](https://img.xkw.com/dksih/QBM/2022/5/9/2975891798867968/2986265880297472/STEM/ce1dca9e-a944-4225-bd1e-d49adf96eaa0.png?resizew=196)
更新时间:2022-05-24 13:16:23
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解答题-证明题
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【推荐1】如图,AB∥CD,AM平分∠BAE,FG平分∠AFC.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/10/18/b7cfc0c6-2ffe-49fe-8eed-f84bdc4d2870.png?resizew=179)
(1)求证:AM∥GF;
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(1)求证:AM∥GF;
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解答题-作图题
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【推荐2】下面是小玲设计的“过直线外一点作已知直线的平行线”的尺规作图过程.
已知:直线l及直线l外一点P.
求作:直线
,使得
.
作法:如图所示.
①在直线l上取一点O,以点O为圆心,
长为半径在直线l上方画半圆,交直线l于A,B两点;
②连接
,以点B为圆心,
长为半径画弧,交半圆于点Q;
③作直线
.
所以直线
就是所求作的直线.
根据小玲设计的尺规作图过程,解决问题:
(1)使用直尺和圆规,补全图形;(保留作图痕迹)
(2)完成下面的证明.
证明:连接
和
,
∵
,
∴
______,
∴
(____________)(填推理的依据),
∴
.
已知:直线l及直线l外一点P.
求作:直线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7a5f1641947153c80b987320885a2b57.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b43460283aa3418a0ed8296ad9ac7eb1.png)
作法:如图所示.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/11/7/95e40e0c-9218-4ba1-bb0d-d761aeefee40.png?resizew=222)
①在直线l上取一点O,以点O为圆心,
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/abd13974aebe38eb2a1d744a01ea5aa5.png)
②连接
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bd33764ff4efddfe11a98a609753715c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/20a541b81584a032f571159ea152c85a.png)
③作直线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7a5f1641947153c80b987320885a2b57.png)
所以直线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7a5f1641947153c80b987320885a2b57.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/11/7/cf6aa90c-fc4b-4da5-a10b-de10cdafdbe2.png?resizew=213)
根据小玲设计的尺规作图过程,解决问题:
(1)使用直尺和圆规,补全图形;(保留作图痕迹)
(2)完成下面的证明.
证明:连接
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2cdba1337ec85fa9722cb4b320a82ae6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cb6ede9761b5b90f8dc137708e1ee90f.png)
∵
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7341c7d3b742bf451457145206782711.png)
∴
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a88ad346a04eb6b20d98edd356264e56.png)
∴
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∴
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