题目
题型:不详难度:来源:
如图,锐角△ABC的内心为I,过点A作直线BI的垂线,垂足为H,点E为内切圆I与边CA的切点.
(Ⅰ)求证:四点A,I,H,E共圆;
(Ⅱ)若∠C=50°,求∠IEH的度数.
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108010921-72139.jpg)
答案
结合IH⊥AH,得∠AEI=∠AHI=90°.
所以,四点A,I,H,E共圆. ……5分
(Ⅱ)由(Ⅰ)知四点A,I,H,E共圆,
得,∠IEH=∠HAI; ……7分
在△HIA中,∠HIA=∠ABI=∠BAI=
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108010921-24445.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108010921-24445.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108010921-24445.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108010921-24445.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108010921-24445.png)
结合IH⊥AH,得∠HAI-90°-∠HIA=
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108010921-24445.png)
所以∠IEH=
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108010921-24445.png)
由∠C=50°,得,∠IEH=25°. ……10分
解析
核心考点
试题【(本小题满分10分)选修4-1:几何证明选讲如图,锐角△ABC的内心为I,过点A作直线BI的垂线,垂足为H,点E为内切圆I与边CA的切点.(Ⅰ)求证:四点A,I】;主要考察你对圆锥曲线性质探讨等知识点的理解。[详细]
举一反三
如图,AB是
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108010914-77207.jpg)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108010914-29365.jpg)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108010915-43679.jpg)
(I) 求证:
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108010915-53364.jpg)
(II) 若BE = 1,DE = 2AE,求DF的长.
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108010915-25454.jpg)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108010909-24405.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108010909-79414.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108010909-34245.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108010909-67352.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108010910-89970.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108010910-10917.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108010909-34245.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108010910-41802.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108010909-67352.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108010910-14691.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108010910-41802.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108010909-34245.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108010911-91106.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108010904-99929.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108010904-95025.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108010904-30297.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108010904-83819.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108010904-48310.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108010905-90313.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108010904-30297.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108010905-41600.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108010904-83819.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108010905-13875.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108010905-41600.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108010904-30297.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108010905-15415.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108010859-23912.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108010859-32080.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108010859-64866.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108010859-23912.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108010859-28810.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108010900-74401.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108010900-77403.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108010900-57926.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108010854-62961.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191108/20191108010854-74404.png)
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