名校
1 . 已知直线
不共面,那么
与
在平面上的投影不可能是( )
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/632244ea6931507f8656e1cc3437d392.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2c94bb12cee76221e13f9ef955b0aab1.png)
A.两条平行线 | B.两条相交直线 |
C.一直线一个点(点不在直线上) | D.两个点 |
您最近一年使用:0次
2 . 坡屋顶是我国传统建筑造型之一,蕴含着丰富的数学元素,安装灯带可以勾勒出建筑轮廓,展现造型之美.如图,某坡屋顶可视为一个五面体,其中两个面是全等的等腰梯形,两个面是全等的等腰三角形.若
,
,且等腰梯形所在的平面,等腰三角形所在的平面与平面ABCD所成角的正切值均为
,则该五面体的所有棱长之和为( )
![](https://img.xkw.com/dksih/QBM/editorImg/2023/11/2/8c33ddc2-f450-4cd9-b8d1-2d5fded2e1cc.png?resizew=175)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/24b7cb51fde25bd56f853ef006770b65.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/de17f729b89e91ebaede5eae236b02da.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bb29a1b25a1bf498d40513169d1b46d0.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/11/2/8c33ddc2-f450-4cd9-b8d1-2d5fded2e1cc.png?resizew=175)
A.![]() | B.![]() | C.![]() | D.![]() |
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解题方法
3 . 如图,直三棱柱
中,
,
,
,外接球的球心为
,点
是侧棱
上的一个动点.有下列判断:
① 直线
与直线
是异面直线;②
一定不垂直
;
③ 三棱锥
的体积为定值; ④
的最小值为
.
![](https://img.xkw.com/dksih/QBM/2017/8/30/1763419974787072/1766336092880896/STEM/c5e1f9af-b9bb-4c30-af44-4f385fb61ef5.png?resizew=281)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/42d3a82b8e587ee890467835bc4e854c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/92535536bd3c2761724fd058427f95a8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/829018a6ca0aff95d89e3f7cd943274e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/45acdbac251ca6b76a166c1242e71df9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e0a851907ada2ac2c3c4880a6736d28a.png)
① 直线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e516121599c9fcc528121c00afcf52fc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9ce1b066f8869d0ff4513f7a99745125.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/24bb49fdc6b6bbb2449fdf8a0de769d3.png)
③ 三棱锥
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/02dd76b7dbe2d9ea408dcac787f89d2d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f998e8cbd8c96e88a6825bf610021970.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/95bacae35b6e16a0a33c2bdc6bc07df7.png)
![](https://img.xkw.com/dksih/QBM/2017/8/30/1763419974787072/1766336092880896/STEM/c5e1f9af-b9bb-4c30-af44-4f385fb61ef5.png?resizew=281)
其中正确的个数是
A.1 | B.2 | C.3 | D.4 |
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