已知正三棱锥P-ABC(底面是正三角形,P在底面的射影是底面的中心),点M,N分别是PA,AB上的动点,MN与底面ABC所成的最大角的正切值为
,则异面直线MN与PC所成的最小角的余弦值为______________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2967337e3fcb228dded64ab0c41a17e0.png)
更新时间:2018-05-07 23:00:19
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适中
(0.65)
解题方法
【推荐1】如图所示,在正四面体
中,
为
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所成角的余弦值是_________ .
![](https://img.xkw.com/dksih/QBM/2016/12/9/1579071033262080/1579071033671680/STEM/3053d63084ae43009e0635e5d49606ac.png?resizew=63)
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适中
(0.65)
解题方法
【推荐2】在正三棱柱
中,
,
为
的中点,则异面直线
与
所成角的余弦值为__________ ;三棱锥
的外接球的表面积为__________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d14f216cb2f1462e551e339743d0b0e6.png)
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名校
解题方法
【推荐1】如图,
在平面
内,
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,则线段PQ在平面
上的射影长为______ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6d7b2fe01a33c4825f9974ed9663a99c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e170f206fdbbd834aad7580c727e2cc6.png)
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填空题-单空题
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解题方法
【推荐2】如图,正方体
的棱长为1,P为侧面
(含边界)内的动点,若直线
与
的夹角为
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![](https://img.xkw.com/dksih/QBM/editorImg/2023/10/30/0b17ddf8-a5a2-424e-a3e2-965fd6286bb8.png?resizew=183)
①点P的运动轨迹的长度为
,
②
的长度为定值
③当CP最小时,三棱锥
的体积为![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d4f669842930533006b4bd7921f2f41a.png)
④存在点P,使得直线
和平面
所成的角为
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e09725691ee7851f54c0dee86b2bf55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5f96c673a2381f118ea2d3efc0bca1f3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7d0ff310aabd2282b539537ebed3f788.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/11ddc92d84d188c66b435664a7e7b5a4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f1e5fa72f2878b476bc57f0df12d6555.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/10/30/0b17ddf8-a5a2-424e-a3e2-965fd6286bb8.png?resizew=183)
①点P的运动轨迹的长度为
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d49f8a63ddbca52039fa9ab44cda6b29.png)
②
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7d0ff310aabd2282b539537ebed3f788.png)
③当CP最小时,三棱锥
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6a00da93b82b518094c4abdc19253022.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d4f669842930533006b4bd7921f2f41a.png)
④存在点P,使得直线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7d0ff310aabd2282b539537ebed3f788.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e22ebcc4aa98d46366df48f751a5f368.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2d5bca00fa20e6e80480b9d06d2e52ee.png)
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