题目
题型:不详难度:来源:
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075506-87060.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075506-18824.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075507-45402.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075507-82661.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075507-56515.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075507-76792.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075508-73341.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075508-23835.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075508-89945.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075509-53566.png)
(1)求∠PEF的度数;
(2)若已知直线
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075509-74060.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075509-36637.png)
答案
解析
∠BEF=180°–∠AEF
=180°–66°=114°.
∵PE平分∠BEF,
∴∠PEF=
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075509-37228.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075509-33724.png)
(2)根据三角形的内角和定理即可求解
∵
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075509-74060.png)
∴∠EFD=∠AEF=66°.
∵PF平分∠EFD,
∴∠PFE=
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075510-66284.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075510-77696.png)
∴
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075509-36637.png)
=180°–57°–33°=90°.
核心考点
举一反三
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075503-19844.png)
A.25º | B.50º | C.65º | D.70º |
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075459-17013.jpg)
(1)画出第10个图并标出相应的数(只需画草图);
(2)数2012应该标在第几个正五边形的哪一个位置上?
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075448-78663.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075448-30810.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075448-95688.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075448-96500.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075448-68372.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075449-40894.png)
求证:△
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075449-54196.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075449-48476.png)
![]() |
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075429-60390.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075429-24861.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075429-26824.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075429-69417.png)
⑴连结
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075429-92383.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075430-86694.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075430-53914.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075430-35171.png)
▲ ;过
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075430-66120.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075430-36860.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075431-76392.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075431-13170.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075431-12256.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075432-89672.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075432-47510.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075432-56136.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075432-97803.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075433-24476.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075433-77120.png)
⑵在图1中,若将三个正方形“退化”为正三角形,得到图3,同学们可以探究△
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075433-37282.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075433-97794.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075434-17841.png)
⑶为了研究问题的需要,将图1中的
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075434-38815.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075434-42890.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075434-42890.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075429-24861.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075434-35618.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075433-37282.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075433-97794.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075433-37282.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075434-65228.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075435-41534.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075435-24518.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075435-41534.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075435-44804.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075434-42890.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075436-50555.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075430-66120.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075435-24518.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075435-41534.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075436-69635.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075436-95194.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075436-65416.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075436-86459.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075437-64611.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075422-12263.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075423-78263.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075423-51720.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103075423-36322.png)
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