题目
题型:不详难度:来源:
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021032705-90009.gif)
(1) 求证:PB//面ACE;
(2) 求二面角E—AC—D的大小。
答案
arctan
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021032705-42582.gif)
解析
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021032705-57192.gif)
解(1)连接BD,设AC与BD相交与点O,连接OE,由BO=OD,PE=ED,有OE//PB,OE
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021032706-75549.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021032706-18538.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021032706-85314.gif)
(2)DF的中点M,过M作MN
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021032706-85476.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021032706-85476.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021032706-85476.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021032707-73002.gif)
EM=
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021032707-73409.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021032707-65643.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021032705-42582.gif)
核心考点
试题【(本题满分12分)四棱锥P—ABCD中,底面ABCD是正方形,侧面PAD是边长为2的正三角形,且侧面PAD与底面ABCD垂直,E为PD的中点。(1) 求证:PB】;主要考察你对空间几何体的结构特征等知识点的理解。[详细]
举一反三
①在空间中,过直线外一点只能作一条直线与该直线平行;
②“直线
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021032700-67392.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021032700-96876.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021032700-67392.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021032700-96876.gif)
③“平面
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021032700-96876.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021032700-55101.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021032700-96876.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021032700-55101.gif)
④若
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021032700-36455.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021032700-24471.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021032700-67392.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021032700-36455.gif)
其中正确命题的个数有 ( )
A.1 | B.2 | C.3 | D.4 |
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021032655-86369.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021032656-42200.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021032656-22599.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021032656-93386.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021032656-22980.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021032656-10026.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021032657-72888.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021032645-66746.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021032646-45233.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021032646-19102.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021032646-36874.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021032646-96677.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021032646-64100.gif)
(1)求证:平面
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021032646-77611.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021032647-92284.gif)
(2)求二面角
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021032647-42982.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021032631-58348.jpg)
如图,在长方体
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021032631-66265.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021032632-74654.gif)
(Ⅰ)证明:
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021032632-95146.gif)
(Ⅱ)当E为AB的中点时,求点A到面
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021032632-16958.gif)
(Ⅲ)AE等于何值时,二面角
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021032632-79986.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021032633-81320.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021032625-47686.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021032625-23562.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021032625-52686.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021032626-64708.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021032626-82923.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021032626-52155.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021032626-56057.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021032627-33757.jpg)
A.![]() | B.![]() | C.![]() | D.与![]() |
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