题目
题型:不详难度:来源:
如题18图,平行六面体
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022080624-33398.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022080625-59554.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022080625-27499.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022080625-31656.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022080625-24126.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022080625-59554.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022080626-24442.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022080626-20726.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022080626-10760.gif)
(Ⅰ)证明:
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022080626-19137.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022080627-43208.gif)
(Ⅱ)求二面角
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022080627-36726.gif)
答案
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022080627-82675.jpg)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022080627-56078.jpg)
解析
核心考点
举一反三
如图,在四棱锥V-ABCD中底面ABCD是正方形,侧面VAD是正三角形,平面VAD
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022080614-28126.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022080615-37072.jpg)
(1)证
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022080615-94429.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022080615-84609.gif)
(2)求面VAD与面VDB所成的二面角的余弦值。
如图在三棱锥P-ABC中,PA
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022080601-54389.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022080602-78900.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022080602-96545.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022080602-61414.jpg)
(1)求证:BC
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022080602-93980.gif)
(2)当D为PB中点时,求AD与平面PAC所成的角的余弦值;
(3)是否存在点E,使得二面角A-DE-P为直二面角,并说明理由。
如图a,在直角梯形
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022080552-47815.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022080552-66504.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022080552-37549.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022080553-12629.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022080553-35694.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022080553-26235.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022080553-65884.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022080554-35409.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022080554-16709.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022080554-17422.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022080554-85665.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022080554-85665.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022080554-15126.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022080555-68999.gif)
(1)求证:
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022080555-59772.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022080555-77642.gif)
(2)求三棱锥
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022080555-47955.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022080544-83410.gif)
如题19图,平行六面体
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022080544-68839.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022080544-34690.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022080544-71181.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022080544-10436.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022080545-88308.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022080544-34690.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022080545-12802.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022080545-33066.gif)
(Ⅰ)证明:
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022080545-77475.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022080546-40104.gif)
(Ⅱ)求二面角
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022080546-57485.gif)
A.![]() | B.![]() | C.![]() | D.![]() |
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