题目
题型:不详难度:来源:
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065504-36874.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065504-65985.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065504-15719.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065505-37112.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065504-36874.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065505-35681.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065505-70467.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065505-24719.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065506-14164.png)
(Ⅰ)求证:
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065506-93773.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065505-35681.png)
(Ⅱ)当
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065506-57469.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065506-55336.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065507-46211.png)
(Ⅲ)求二面角
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065507-90927.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065507-57724.jpg)
答案
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065507-13922.png)
∴四边形ABCD是等腰梯形,
且
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065507-60904.png)
∴
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065508-24323.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065508-42162.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065508-86852.jpg)
又∵平面
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065508-25704.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065509-87316.png)
(Ⅱ)当
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065509-89949.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065509-28983.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065509-78184.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065510-95008.png)
∵
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065509-89949.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065510-65232.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065510-73719.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065510-38168.png)
∴四边形ANFM是平行四边形. ∴
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065510-64136.png)
又∵
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065511-36176.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065511-71763.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065509-28983.png)
(Ⅲ)取EF中点G,EB中点H,连结DG、GH、DH,∵DE=DF,∴
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065511-91010.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065509-87316.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065511-92162.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065512-77483.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065512-28122.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065512-27843.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065512-47950.png)
∴
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065513-42842.png)
在△BDE中
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065513-32008.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065513-41724.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065513-90311.png)
∴
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065513-77344.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065514-77935.png)
由余弦定理得
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065514-81238.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065514-35068.png)
解析
核心考点
举一反三
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065451-16105.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065451-44715.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065451-15108.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065452-64745.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065452-12270.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065452-26509.png)
(Ⅰ)求证:平面
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065452-42891.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065452-91909.png)
(Ⅱ)求
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065453-79880.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065453-62324.png)
(Ⅲ)求
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065453-54569.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065453-87458.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065454-10237.jpg)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065440-33585.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065440-95027.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065441-12231.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065441-26304.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065441-71272.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065441-64630.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065442-49388.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065442-57304.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065442-58818.jpg)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065431-11506.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065431-37797.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065431-44958.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065431-82214.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065431-93613.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065432-88426.png)
(1)求证:
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065432-11114.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065432-31592.png)
(2)求二面角
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065432-85044.png)
(3)求点
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065433-93502.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065433-76778.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065433-98824.jpg)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065423-18819.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065423-11259.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065423-11162.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065423-18819.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065423-11259.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065423-11259.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065423-11162.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065423-18819.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065423-11162.png)
A.相交 | B.平行 | C.异面 | D.以上均有可能 |
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065417-69245.png)
(1)求圆锥的体积.
(2)当
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065417-69245.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022065417-77441.jpg)
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