名校
1 . 已知等边三角形
的边长为
,
分别为
的中点,将
沿
折起至
,在四棱锥
中,下列说法正确的序号是___________ .
①直线
平面![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e4e762b6254e43bab7ca4a34201845d0.png)
②当四棱锥
体积最大时,二面角
为直二面角
③在折起过程中存在某位置使
平面![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d7c5d45898d3bfd7cad3ea3830d06f5f.png)
④当四棱
体积最大时,它的各顶点都在球
的球面上,则球
的表面积为
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6f8c4c029e552954bd493b49aeab82d5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7789a500686c7a73770404ead6af0590.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7dec2ca6438c82b43f746057d8129885.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e5a9fc2dda89829fa2c610a8fce86d22.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411461db15ee8086332c531e086c40c7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e8e7040c2fd8a163d71e35805775feb8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d25c1f004fbf481518e0c14bf1bda6b3.png)
①直线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/edcf19a7f0dd0cdf59516ae585025110.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e4e762b6254e43bab7ca4a34201845d0.png)
②当四棱锥
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d25c1f004fbf481518e0c14bf1bda6b3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4085d6be6b34d6266e16164c60bbe50b.png)
③在折起过程中存在某位置使
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d6da9f598fecf6fcf41cd65b45cbe08.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d7c5d45898d3bfd7cad3ea3830d06f5f.png)
④当四棱
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d25c1f004fbf481518e0c14bf1bda6b3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a628810c9dc52aa96f3eb68c34361be1.png)
您最近一年使用:0次
2 . 在正方体
中,有如下命题:
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/7/3fbc1520-c66f-4024-b468-3d1241ae521f.png?resizew=162)
①两条异面直线
和
所成的角为
;
②直线
与平面
所成的角为
;
③若
是棱
中点,则直线
与
是相交直线;
④若点
在线段
上运动,则始终有
.
真命题的个数为( )
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e09725691ee7851f54c0dee86b2bf55.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/7/3fbc1520-c66f-4024-b468-3d1241ae521f.png?resizew=162)
①两条异面直线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e539f26ed5e0b20ff7220559324869a4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0d8772aa893a9c1d40f714cb25701701.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/af9955b5aebb73cd84447e8541f901ac.png)
②直线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/679748eab882a6be0fefd2cc300349a4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/af9955b5aebb73cd84447e8541f901ac.png)
③若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f66fb71b75b63594ebeeeebd1963eed5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d50703c46b6153945d718b198f03b4b5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d88bf46ad08f9677c37eed1d0369329.png)
④若点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83c09eec4e14a861af83d7828797d176.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/763be97fe1e030b5509bda231a546001.png)
真命题的个数为( )
A.1 | B.2 | C.3 | D.4 |
您最近一年使用:0次