把一个半圆对折两次(如图),折痕OA与OB的夹角为( )
![](https://img.xkw.com/dksih/QBM/2016/3/23/1574186506076160/1574186512195584/STEM/a61b90b6cb8346568a951d6df7329f2b.png)
![](https://img.xkw.com/dksih/QBM/2016/3/23/1574186506076160/1574186512195584/STEM/a61b90b6cb8346568a951d6df7329f2b.png)
A.45° | B.60° | C.90° | D.120° |
更新时间:2016-12-06 11:53:34
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【推荐1】如图,将一张长方形纸片
沿
折叠,点A,B分别落在点
,
的位置上,
与
交于点
,若
,则
( )
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A.![]() | B.![]() | C.![]() | D.![]() |
您最近一年使用:0次
单选题
|
较易
(0.85)
【推荐2】将三角形纸片
按如图所示的方式折叠,使点
落在边
上,记为点
,折痕为
.已知
,
,若
,那么
的长度是( )
![](https://img.xkw.com/dksih/QBM/editorImg/2024/1/3/d313dcda-94b7-43d0-9777-b26d80d40e3e.png?resizew=165)
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A.![]() | B.4 | C.![]() | D.2 |
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