题目
题型:不详难度:来源:
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021024627-62007.gif)
长方体ABCD-A1B1C1D1的侧棱AA1的长是a,底面ABCD的边长AB=2a,BC=a,E为C1D1的中点。
(1)求证:DE⊥平面BCE;
(2)求二面角E-BD-C的正切值。
答案
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021024627-34486.jpg)
解析
核心考点
试题【(本小题满分10分)长方体ABCD-A1B1C1D1的侧棱AA1的长是a,底面ABCD的边长AB=2a,BC=a,E为C1D1的中点。(1)求证:DE⊥平面BC】;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
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021024616-80886.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021024616-76345.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021024616-73163.gif)
点
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021024616-85148.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021024617-85062.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021024617-98263.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021024617-16608.gif)
(Ⅰ)求证:
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021024617-97639.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021024617-65183.gif)
(Ⅱ)当
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021024616-85148.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021024618-70953.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021024618-35458.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021024617-65183.gif)
(Ⅲ)是否存在点
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021024617-85062.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021024618-20926.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021024618-63758.jpg)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021024611-67404.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021024611-67404.gif)
A.三角形 | B.矩形 | C.梯形 | D.以上都不对 |
①若直线
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021024608-34922.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021024608-49745.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021024608-34922.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021024608-21826.gif)
②若直线
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021024608-34922.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021024608-49745.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021024608-34922.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021024608-49745.gif)
③直线
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021024608-79404.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021024608-49745.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021024609-31028.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021024608-21826.gif)
A.0 | B.1 | C.2 | D.3 |
在长方体
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021024558-48050.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021024558-77848.gif)
(1) 求证:
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021024558-66278.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021024558-22645.gif)
(2) 证明:
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021024559-40309.gif)
(3) 一只蜜蜂在长方体
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021024558-48050.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021024559-26071.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021024559-31462.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021024550-15976.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021024551-94388.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021024551-99727.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021024551-41093.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021024551-93616.gif)
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