已知直三棱柱
的底面为直角三角形,且内接于球O,若此三棱柱
的高为2,体积是1,则球O的半径的最小值为___________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/42d3a82b8e587ee890467835bc4e854c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/42d3a82b8e587ee890467835bc4e854c.png)
2021·广西·模拟预测 查看更多[2]
更新时间:2020-12-13 11:21:26
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【知识点】 多面体与球体内切外接问题
相似题推荐
填空题-双空题
|
较难
(0.4)
名校
解题方法
【推荐1】在一个正方形
内有一个小正方形ABCD和四个全等的等边三角形(如图1).将四个等边三角形折起来,使
、
、
、
重合于点P,且折叠后的四棱锥
(如图2)的外接球的表面积是
,则四棱锥
的侧棱PA的长为______ ;若在四棱锥
内放一个正方体,使正方体可以在四棱锥
内任意转动,则该正方体棱长的最大值为______ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/76b2e5c0987bf8ceee3e700fc086a35e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2708fa6298e52f617383efc175b71ddc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9b9cb8e6ff801523b0304576cd69fd2d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/797e67927616b141ed7c6b83f8b6f4fb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fee50575e3ebd56c4f46dd0bbf8e55d3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0585b6c0f156eecf9662b9846d4eb693.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/178ec48ec6dec55778c74962a928d600.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0585b6c0f156eecf9662b9846d4eb693.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0585b6c0f156eecf9662b9846d4eb693.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0585b6c0f156eecf9662b9846d4eb693.png)
![](https://img.xkw.com/dksih/QBM/2022/4/26/2966617169068032/2968880114737152/STEM/3a39792d-af43-4843-85fc-28aafef13118.png?resizew=408)
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填空题-单空题
|
较难
(0.4)
名校
解题方法
【推荐2】已知矩形
的长
,宽
,将其沿对角线
折起,得到四面体
,如图所示,
![](https://img.xkw.com/dksih/QBM/editorImg/2023/3/1/fb5f8974-ec6c-4632-b8a2-a1bc1b1a8f81.png?resizew=296)
给出下列结论:
①四面体
体积的最大值为
;
②四面体
外接球的表面积恒为定值;
③若
分别为棱
的中点,则恒有
且
;
④当二面角
的大小为
时,棱
的长为
;
⑤当二面角
为直二面角时,直线
所成角的余弦值为
.
其中正确的结论有_____________________ (请写出所有正确结论的序号).
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d2c15801fee2405573677484f5dcfa4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d0d5a2cd05e4476fc72271e8fdb59a9a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d40b319212a7e7528b053e1c7097e966.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/891579e7c231584a8e16b8eeff79888e.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/3/1/fb5f8974-ec6c-4632-b8a2-a1bc1b1a8f81.png?resizew=296)
给出下列结论:
①四面体
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/891579e7c231584a8e16b8eeff79888e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/93b1079a0333d5598c214bd2f556b0a7.png)
②四面体
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/891579e7c231584a8e16b8eeff79888e.png)
③若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3cf9b288c48c73463a2f214f02b6952a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2d578394cd8e4d7a705599269c512960.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8de4a54cc7818be87a239f6de5f5d05b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c672f693a7e75a7bae4936dcb1920430.png)
④当二面角
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5f1854ba6cc92481d7a616bd2788a47e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/260200d547998bcac50a4a491382e7f4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/daa318599ebbca8120b38bb1904a9dac.png)
⑤当二面角
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5f1854ba6cc92481d7a616bd2788a47e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c28d2790a97390935125aa897417f970.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/482b71ca0f34940dc775e6666e010c8f.png)
其中正确的结论有
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