题目
题型:不详难度:来源:
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106153215-37262.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106153215-37262.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106153216-81244.jpg)
小题1:若四边形ABCD为正方形,当
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106153215-37262.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106153216-32697.png)
小题2:如图2,如果四边形ABCD中,AB=AD,
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106153215-37262.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106153215-37262.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106153215-37262.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106153216-28396.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106153215-37262.png)
小题3:在(2)中,若BC=4,DC=7,CF=2,求
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106153216-14796.png)
答案
小题1:EF=DF-BE
小题2:EF=DF-BE。
证明:在DF上截取DM=BE,连接AM。如图,
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106153217-51926.jpg)
∵
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106153215-37262.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106153215-37262.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106153215-37262.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106153215-37262.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106153217-41082.png)
∴
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106153215-37262.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106153215-37262.png)
∵AD=AB,
∴
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106153216-14796.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106153216-14796.png)
∴AM=AE,
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106153215-37262.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106153215-37262.png)
∵
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106153215-37262.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106153215-37262.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106153215-37262.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106153216-28396.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106153215-37262.png)
∴
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106153215-37262.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106153215-37262.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106153216-28396.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106153215-37262.png)
∴
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106153215-37262.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106153216-28396.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106153215-37262.png)
∴
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106153215-37262.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106153215-37262.png)
∵AF是
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106153216-14796.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106153216-14796.png)
∴
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106153216-14796.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106153216-14796.png)
∴EF=MF。
∵MF=DF-DM=DF-BE,
∴EF=DF-BE。
小题3:
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106153216-14796.png)
解析
(3)根据前三问的结论知:EF=DF-BE,那么△CEF的周长可转化为:EF+BE+BC+FC=DF+BC+FC,即可得解.
核心考点
试题【如图1,将EAF绕着四边形ABCD的顶点A顺时针旋转,EAF的两边分别与DC的延长线交于点F,与CB的延长线交于点E,连接EF。小题1:若四边形ABCD为正方形】;主要考察你对轴对称等知识点的理解。[详细]
举一反三
小题1:如图,将△ABC绕点O顺时针旋转180°后得到△
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106153210-24955.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106153210-24955.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106153210-79199.png)
小题2:请你画出下面“蒙古包”的左视图.(4分)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106153211-18339.png)
A.等边三角形 | B.平行四边形 | C.梯形 | D.矩形 |
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106153202-49009.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106153155-99445.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106153155-10512.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106153156-61253.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106153156-12046.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106153156-21526.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106153156-79916.png)
小题1:画出旋转后的
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106153156-79916.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106153157-38556.png)
小题2:求在旋转过程中,点
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106153157-60987.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106153157-18409.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106153157-94018.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106153158-51112.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106153147-23753.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106153147-40911.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106153147-40911.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106153147-34250.png)
A.![]() | B.![]() | C.![]() | D.![]() |
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