题目
题型:不详难度:来源:
如图,在四棱锥P-ABCD中,底面ABCD为正方形,且PD
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022073812-36726.gif)
(I)证明:EF//平面PCD
(II)求二面角B-CE-F的大小
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022073813-82157.jpg)
答案
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022073813-49858.gif)
如图,取PC中点M,易知:
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022073813-50905.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022073813-50895.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022073813-10161.gif)
又
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022073814-39769.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022073813-10161.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022073814-19448.gif)
(Ⅱ)∵
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022073814-19067.gif)
∴
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022073814-75550.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022073815-83673.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022073815-87909.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022073815-66195.gif)
∴二面角B-CE-F为
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022073815-39842.gif)
解析
核心考点
试题【(本小题满分12分)如图,在四棱锥P-ABCD中,底面ABCD为正方形,且PD平面ABCD,PD=AB=1,E,F分别是PB,AD的中点(I)证明:EF//平面】;主要考察你对线线角等知识点的理解。[详细]
举一反三
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022073804-14991.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022073804-38164.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022073804-15910.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022073805-63080.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022073805-52175.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022073805-45938.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022073805-99300.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022073806-89231.png)
A.9 | B.10 | C.11 | D.12 |
(本小题满分15分)
已知四棱锥
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022073752-36467.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022073752-82495.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022073752-65152.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022073756-67608.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022073756-71423.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022073756-78897.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022073756-27457.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022073756-96001.gif)
(Ⅰ)证明:面
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022073756-76674.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022073756-33220.gif)
(Ⅱ)求
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022073756-45299.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022073756-96001.gif)
(Ⅲ)求面
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022073756-17325.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022073757-95406.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022073744-40014.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022073744-31780.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022073745-75100.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022073745-21142.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022073745-24178.png)
A.若![]() ![]() |
B.若![]() ![]() |
C.若![]() ![]() |
D.若![]() ![]() |
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022073729-68248.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022073729-72782.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022073730-10108.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022073730-92097.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022073729-72782.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022073730-79547.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022073730-46412.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022073730-65893.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022073731-52444.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022073731-48792.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022073731-66842.gif)
(Ⅰ)求证:
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022073731-82389.gif)
(Ⅱ)求多面体
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022073732-70920.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022073732-63444.jpg)
如图,在四棱锥
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022073721-75806.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022073721-75390.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022073721-53099.gif)
底面
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022073721-53099.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022073722-43425.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022073722-36408.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022073722-32325.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022073722-23140.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022073722-77748.gif)
(1)求证:
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022073723-33411.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022073723-24860.gif)
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