题目
题型:不详难度:来源:
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022054959-93993.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022054959-64052.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022054959-95146.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022054959-91596.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022055000-44022.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022054959-64052.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022054959-91596.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022054959-95146.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022055000-44022.png)
A.75° | B.60° | C.45° | D.30° |
答案
解析
试题分析:易知
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022055000-55047.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022055000-78548.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022055000-89135.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022055000-83510.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022055001-55259.png)
点评:二面角求解的一般步骤: 一、“找”:找出图形中二面角,若不能直接找到可以通过作辅助线补全图形找二面角的平面角。 二、“证”:证明所找出的角就是该二面角的平面角。三、“算”:计算出该平面角。
核心考点
试题【椭圆的长轴为,短轴为,将椭圆沿y轴折成一个二面角,使得点在平面上的射影恰好为椭圆的右焦点,则该二面角的大小为( ).A.75°B.60° C.45°D.3】;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/20191022/20191022054954-92205.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022054954-80393.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022054954-82947.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022054954-53857.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022054955-21600.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022054955-59453.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022054955-14018.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022054955-74415.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022054939-95102.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022054939-74424.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022054939-52361.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022054939-95102.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022054939-83410.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022054939-93104.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022054939-98479.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022054939-95102.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022054940-77073.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022054940-89527.jpg)
(Ⅰ)求证:
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022054940-30568.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022054940-77942.png)
(Ⅱ)求二面角
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022054940-93611.png)
(Ⅲ)线段
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022054940-77666.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022054940-59282.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022054941-92326.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022054941-32547.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022054940-59282.png)
如图:四棱锥P-ABCD中,底面ABCD是平行四边形,∠ACB=90°,PA⊥平面ABCD,PA=BC=1,AB=
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022054928-66855.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022054928-64300.png)
(Ⅰ)求证:DA⊥平面PAC;
(Ⅱ)点G为线段PD的中点,证明CG∥平面PAF;
(Ⅲ)求三棱锥A—CDG的体积.
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022054913-79234.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022054913-89015.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022054914-44882.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022054914-15840.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022054914-87579.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022054914-87584.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022054914-89171.png)
(Ⅰ)证明:
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022054915-61780.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022054915-41072.png)
(Ⅱ)求二面角
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022054915-11311.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022054900-73664.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022054900-64251.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022054900-88760.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022054901-99344.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022054901-77850.png)
(Ⅰ)求证:平面
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022054901-78813.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022054901-87263.png)
(Ⅱ)若
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022054902-38480.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022054902-46089.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022054902-64297.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022054902-58547.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022054903-99168.png)
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