题目
题型:不详难度:来源:
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080725-29058.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080725-93868.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080726-99472.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080726-25659.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080726-80261.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080726-53514.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080726-69019.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080727-99780.png)
(I)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080727-78138.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080727-51739.png)
(II)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080727-99895.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080728-34175.png)
(Ⅲ)求二面角
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080728-45947.png)
答案
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080728-20401.png)
解析
试题分析:由三视图知,四边形
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080728-26574.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080728-60691.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080729-60279.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080729-22328.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080729-18611.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080729-68805.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080730-10259.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080725-29058.png)
(1)连接
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080730-54484.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080730-17066.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080730-59548.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080730-53268.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080731-50106.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080727-51739.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080731-38339.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080727-51739.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080730-10259.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080727-78138.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080727-51739.png)
(2)法一:在
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080731-39758.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080731-83894.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080731-85521.png)
同理在
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080732-78077.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080732-12953.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080732-79390.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080732-77550.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080730-10259.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080733-59651.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080733-31064.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080733-87632.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080733-59432.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080734-99203.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080734-39372.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080730-10259.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080734-59327.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080734-33379.png)
又
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080734-75320.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080730-10259.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080727-99895.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080728-34175.png)
法二:如图以
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080735-69728.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080735-49954.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080735-36011.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080735-30008.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080736-62283.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080736-44622.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080736-88814.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080736-62542.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080736-89107.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080737-95880.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080737-22091.png)
设面
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080737-42375.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080737-45987.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080738-50430.png)
取
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080738-72134.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080738-29881.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080737-42375.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080738-35952.png)
所以
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080738-50211.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080730-10259.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080727-99895.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080728-34175.png)
(3)如图以
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080735-69728.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080735-49954.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080735-36011.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080735-30008.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080736-62283.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080736-44622.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080736-88814.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080736-62542.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080739-32834.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080739-15342.png)
因为
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080739-27761.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080739-51447.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080740-64994.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080739-51447.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080740-48825.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080740-39080.png)
设面
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080737-42375.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080737-45987.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080738-50430.png)
取
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080738-72134.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080738-29881.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080737-42375.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080738-35952.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080740-24426.png)
所以二面角
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080740-48029.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080728-20401.png)
点评:判断线面平行的常用方法:①应用线面平行的判断定理,即由线线平行推线面平行;②应用面面平行的性质定理,即由面面平行证明线面平行;③向量法。
核心考点
试题【几何体的三视图如图,与交于点,分别是直线的中点, (I)面;(II)面;(Ⅲ)求二面角的平面角的余弦值.】;主要考察你对空间几何体的视图与直观图等知识点的理解。[详细]
举一反三
A.各个面都是三角形的几何体是三棱锥 |
B.以三角形一条边所在直线为旋转轴,其余两边旋转形成的曲面所围成的几何体叫圆锥 |
C.棱锥的侧棱长与底面多边形的边长相等,则该棱锥可能是六棱锥 |
D.圆锥的顶点与底面圆周上的任意一点的连线都是母线 |
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080717-65188.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080718-59835.jpg)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080713-47465.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080714-26555.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080714-26555.png)
A.增函数且有最大值 | B.增函数且没有最大值 |
C.不是增函数且有最大值 | D.不是增函数且没有最大值 |
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080705-19474.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021080705-24462.jpg)
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