设面积为S的平面四边形的第
条边的边长为
,P是该四边形内一点,点P到第
条边的距离记为
,若
,则
,类比上述结论,体积为V的三棱锥的第
个面的面积记为
,Q是该三棱锥内的一点,点Q到第个面的距离记为
,若
等于______ .
![](https://img.xkw.com/dksih/QBM/2012/7/10/1570920261279744/1570920266506240/STEM/547733bf309b459ba81f09cd89f1a84c.png?resizew=9)
![](https://img.xkw.com/dksih/QBM/2012/7/10/1570920261279744/1570920266506240/STEM/04ab0a39247b4688b804f3ca062a738f.png?resizew=96)
![](https://img.xkw.com/dksih/QBM/2012/7/10/1570920261279744/1570920266506240/STEM/547733bf309b459ba81f09cd89f1a84c.png?resizew=9)
![](https://img.xkw.com/dksih/QBM/2012/7/10/1570920261279744/1570920266506240/STEM/1abbb653394849d7b988aca7505c90ff.png?resizew=16)
![](https://img.xkw.com/dksih/QBM/2012/7/10/1570920261279744/1570920266506240/STEM/bd8be299d01b4669b633d3f7e06e6c0a.png?resizew=152)
![](https://img.xkw.com/dksih/QBM/2012/7/10/1570920261279744/1570920266506240/STEM/f924782c0bd540b59ae84606715cd1b2.png?resizew=88)
![](https://img.xkw.com/dksih/QBM/2012/7/10/1570920261279744/1570920266506240/STEM/547733bf309b459ba81f09cd89f1a84c.png?resizew=9)
![](https://img.xkw.com/dksih/QBM/2012/7/10/1570920261279744/1570920266506240/STEM/253ec176e3ea455b8efbe6d375c5aed3.png?resizew=96)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f50a4b1e4f8b1d044300df7ef8205c31.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/040373d55f6b89e02094e146009e605f.png)
2012·河北衡水·一模 查看更多[2]
更新时间:2016-12-01 21:26:32
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【推荐1】已知“在
中,
”,类比以上正弦定理,“在三棱锥
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________ .
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填空题-单空题
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较易
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【推荐2】在平面几何里有射影定理:“设
的两边
,
是
点在
边上的射影,则
”扩展到空间,若三棱锥
的三个侧面
、
、
两两互相垂直,点
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