题目内容
若正四棱柱
的底面边长为2,高为4,则异面直线![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824001118736458.png)
所成角的正切值是_________________.![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/201408240011187837606.jpg)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824001118721787.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824001118736458.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824001118752389.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/201408240011187837606.jpg)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824001118814305.png)
试题分析:根据正四棱柱的几何特征,我们易根据AD∥BC,得到∠D1BC即为异面直线BD1与AD所成角,根据已知中正四棱柱ABCD-A1B1C1D1的底面边长为2,高为
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824001118830248.png)
∵AD∥BC∴∠D1BC即为异面直线BD1与AD所成角连接D1C,在△D1BC中,∵正四棱柱ABCD-A1B1C1D1的底面边长为2,高为4∴D1B=2
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824001118845341.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824001118861415.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824001118877496.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824001118814305.png)
故答案为
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824001118814305.png)
点评:解决该试题的关键是根据已知条件确定找到两条异面直线夹角,易根据AD∥BC,得到∠D1BC即为异面直线BD1与AD所成角
![](http://thumb.zyjl.cn/images/loading.gif)
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