题目内容
已知:如图,矩形
,
平面
,
分别是
的中点,
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/201408231500487516580.jpg)
(1)求证:直线
直线
,
(2)若平面
与平面
所成的锐二面角为
,能否确定
使直线
是异面直线
与
的公垂线.若能确定,求出
的值;若不能确定,说明理由。
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150048673326.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150048689266.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150048673326.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150048720395.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150048736330.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/201408231500487516580.jpg)
(1)求证:直线
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150048767412.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150048798250.gif)
(2)若平面
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150048814280.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150048673326.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150048845209.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150048845209.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150048876381.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150048798250.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150048923238.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150048845209.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150048954310.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150048876381.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150048798250.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150048923238.gif)
(1)证明:取
中点
,连结
,
则![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049063252.gif)
,![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049141375.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049079143.gif)
,
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049141375.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049079143.gif)
,
四边形
为平行四边形,
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049188130.gif)
//
。
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049391183.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049407238.gif)
平面
,
平面![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049453282.gif)
平面
,
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049391183.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150048798250.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049422114.gif)
,![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049188130.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150048798250.gif)
平面
,
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049188130.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150048798250.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049422114.gif)
,![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049188130.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150048876381.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049422114.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150048798250.gif)
(2)![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049391183.gif)
//
,
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049188130.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049828250.gif)
平面
,![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049188130.gif)
为二面角
的平面角,
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049188130.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049921304.gif)
,
若
为
,
的公垂线,
则![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049375241.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049422114.gif)
,又![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049828250.gif)
平面
,
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049188130.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049375241.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049422114.gif)
,![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049188130.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049375241.gif)
平面
,
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049188130.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049375241.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049422114.gif)
,![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049391183.gif)
为
中点,![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049188130.gif)
,
于是可以确定
时,
为
,
的公垂线。
高&考%资(源
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049001244.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049032206.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049048439.gif)
则
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049063252.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049079143.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049126332.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049141375.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049079143.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049126332.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049188130.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049141375.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049079143.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049063252.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049188130.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049313448.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049188130.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150048876381.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049375241.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049391183.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049407238.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049422114.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150048673326.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049188130.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049453282.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049422114.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150048673326.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049391183.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150048798250.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049422114.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049563254.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049188130.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150048798250.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049422114.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049453282.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049188130.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150048798250.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049422114.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049375241.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049188130.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150048876381.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049422114.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150048798250.gif)
(2)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049391183.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150048798250.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049828250.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049188130.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049828250.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049422114.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049453282.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049188130.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049921304.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049937346.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049188130.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049921304.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150050140223.gif)
若
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150048876381.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150048798250.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150048923238.gif)
则
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049375241.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049422114.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150048923238.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049828250.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049422114.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049453282.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049188130.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049375241.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049422114.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049828250.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049188130.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049375241.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049422114.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150050452278.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049188130.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049375241.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049422114.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049001244.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049391183.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049032206.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049001244.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150049188130.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150048954310.gif)
于是可以确定
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150048954310.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150048876381.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150048798250.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823150048923238.gif)
高&考%资(源
![](http://thumb2018.1010pic.com/images/loading.gif)
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