题目
题型:不详难度:来源:
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021064945-91102.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021064945-16821.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021064945-83500.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021064946-45088.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021064946-48266.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021064946-32980.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021064946-28320.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021064946-63118.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021064947-50707.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021064947-30064.png)
A.点![]() ![]() |
B.直线![]() ![]() |
C.三棱锥![]() |
D.二面角![]() |
答案
解析
试题分析:A选项中,∵QEF平面也就是平面A1B1CD,既然P和平面QEF都是固定的,所以点
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021064945-83500.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021064947-55395.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021064945-83500.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021064947-55395.png)
B选项中,∵Q是动点,EF也是动点,推不出定值的结论,所以就不是定值.∴直线
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021064947-51584.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021064948-54695.png)
C选项中,∵△QEF的面积是定值.(因为EF定长,Q到EF的距离就是Q到CD的距离也为定长,即底和高都是定值),再根据1的结论P到QEF平面的距离也是定值,所以三棱锥的高也是定值,于是体积固定.∴三棱锥
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021064948-63210.png)
D选项中,∵A1B1∥CD,Q为A1B1上任意一点,E、F为CD上任意两点,∴二面角
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021064948-68780.png)
核心考点
试题【如图,在棱长为的正方体中,为的中点,为上任意一点,为上任意两点,且的长为定值,则下面四个值中不为定值的是A.点到平面的距离B.直线与平面所成的角C.三棱锥的体积】;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
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021064936-53185.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021064936-45702.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021064937-15947.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021064937-55526.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021064937-95149.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021064937-82847.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021064936-53185.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021064937-11086.png)
(1)求证:平面
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021064938-79623.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021064938-68630.png)
(2)求三棱锥
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021064938-40241.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021064931-96979.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021064931-13141.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021064932-55387.jpg)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021064920-49675.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021064921-60447.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021064921-71871.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021064921-59973.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021064921-71494.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021064921-71871.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021064922-11988.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021064921-60447.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021064922-19786.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021064922-70085.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021064922-48275.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021064923-10885.jpg)
(1)证明:平面
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021064923-79474.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021064923-44716.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021064923-84796.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021064923-90999.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021064914-57733.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021064914-94329.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021064914-63229.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021064914-91180.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021064914-94329.png)
A.![]() | B.![]() | C.![]() | D.![]() |
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021064909-40720.png)
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