1 . 如图,边长为
的正方体
与棱长为
的正四面体
位于平面
的同侧,
.在正方体的六个面所在的平面中,与直线
相交的平面记为
(
,2,3,……),
在平面
内的射影长为
,则所有射影长
的和为( )
![](https://img.xkw.com/dksih/QBM/editorImg/2023/1/15/7d16abe0-e998-4d6d-a0bf-348ced7b2840.png?resizew=356)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e09725691ee7851f54c0dee86b2bf55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d9bbc7e0de28c652ae10a8db5b4e2687.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e170f206fdbbd834aad7580c727e2cc6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e41d3f7d55fcbaebc4e2450ac63a3dc5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4505508b3e36db64a207dcdaf8eb22dc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/24fec5bd42f9e083fa427a2e942103ae.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7c45176df950dfe48b8ca7eac08ee349.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4505508b3e36db64a207dcdaf8eb22dc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/24fec5bd42f9e083fa427a2e942103ae.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/468edcfef1bcd7e74491a57a70c1bcb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/468edcfef1bcd7e74491a57a70c1bcb1.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/1/15/7d16abe0-e998-4d6d-a0bf-348ced7b2840.png?resizew=356)
A.![]() | B.![]() | C.![]() | D.![]() |
您最近一年使用:0次
解题方法
2 . 如图所示,用一束与平面
成
角的平行光线照射半径为
的球
,在平面
上形成的投影为椭圆
及其内部,则椭圆
的( )
![](https://img.xkw.com/dksih/QBM/2021/4/25/2707625932054528/2736416918962176/STEM/67c76b6f-7db0-40ed-a6fd-d08958297ca6.png?resizew=252)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e170f206fdbbd834aad7580c727e2cc6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2d5bca00fa20e6e80480b9d06d2e52ee.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a7ffe8515ff6183c1c7775dc6f94bdb8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e170f206fdbbd834aad7580c727e2cc6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://img.xkw.com/dksih/QBM/2021/4/25/2707625932054528/2736416918962176/STEM/67c76b6f-7db0-40ed-a6fd-d08958297ca6.png?resizew=252)
A.长轴长为![]() | B.离心率为![]() | C.焦距为![]() | D.面积为![]() |
您最近一年使用:0次