解题方法
1 .
中,
,作
,点
为垂足,
为
在
上的射影,
为
在
上的射影,则有
成立.直角四面体
(即
)中,点
为点
在平面
内的射影,
的面积分别为
,且
在平面
内的射影分别为
、
,其面积分别为
的面积记为
,类比直角三角形中的射影结论,在直角四面体
中可得到的正确结论为______ .(写出一个正确结论即可).
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1ce7f6d278f2ef7a193b7eed7be6b3c5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6f8e9ec412ea0355e4e5cd06c60e5fee.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8b5f215a42c4b7078d8d65923eb9980e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d40b319212a7e7528b053e1c7097e966.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a6fc3d6ccd1273f5264fbe379917ac32.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63397cda22cb1fad59cf966dfb588643.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a9b32d28f87339224b79072f83005d68.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/31c80eb47003139afbff206cad09442c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fcf4e20ea341827ce5f9552daee39462.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/31c80eb47003139afbff206cad09442c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/257e807bf73207b5cd35a19a6c023bbc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2bbf9680f74a9ac5d934304654ce2771.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a43295b4f7d1d1750d56bec08ba7b0c6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cf231f8f86fb922df4ca0c87f044cec3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63397cda22cb1fad59cf966dfb588643.png)
您最近一年使用:0次
10-11高二·黑龙江·阶段练习
2 .
中,
,D为垂足,BD为AB在BC上的射影,CD为AC在BC上的射影,则有
成立.直角四面体P—ABC(即
)中,O为P在
内的射影,
的面积分别为
的面积记为S.类比直角三角形中的射影结论,在直角四面体P—ABC中可得到正确结论_____ .(写出一个正确结论即可)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cfa8cee7d2463f6f7d352e8b65f47cf3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3fdbd90f52ca8bb03c8ac8c5e9092b0a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/672516eb3d2811bda2a5d53b43a8b05d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a9b32d28f87339224b79072f83005d68.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ad06904598a3bca701a0f786ab3fd6ff.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c47206849bfb4874ffd87a49bb35b863.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8d9150413bd8ee2b05df9e08d77ea30b.png)
您最近一年使用:0次
2011·辽宁·二模
3 . Rt△ABC中,∠BAC=90°,作AD⊥BC,D为垂足,BD为AB在BC上的射影,CD为AC在BC上的射影,则有AB2+AC2=BC2成立.直角四面体P﹣ABC(即PA⊥PB,PB⊥PC,PC⊥PA)中,O为P在△ABC内的射影,△0AB,△0BC,△0CA的面积分别记为S1,S2,S3,△ABC的面积记为S.类比直角三角形中的射影结论,在直角四面体P﹣ABC中可得到正确结论_____ .(写出一个正确结论即可)
您最近一年使用:0次
名校
4 .
内角和我们可以这样理解:一根可自由伸缩的棍子(不考虑它的长度,棍子的一端有箭头),从状态1(与
重合)绕点A逆时针旋转大小为
的旋转量到状态2(与
重合),再绕点C逆时针旋转大小为
旋转量到状态3(与
重合),最后绕点B逆时针旋转大小为
的旋转量变为状态4,棍子回到了与
重合的状态,棍子逆时针转了半圈(棍子两端已互换),因此得到旋转量之和
.
![](https://img.xkw.com/dksih/QBM/2021/3/28/2687822354350080/2689861230362624/STEM/604ca13a95144bf3a15f06e0a3d4008a.png?resizew=309)
![](https://img.xkw.com/dksih/QBM/2021/3/28/2687822354350080/2689861230362624/STEM/2f535de3a4d94f46999fac57388b121a.png?resizew=218)
给出下列多边形中的8个角:
(如图标注),根据你对上述阅读材料的理解,请你建立这8个角的一个等量关系,则等式为___________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3818a2c9919d358b4c3713396093822b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/194741f4d2ae7ee44cafca780361446a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6b1bd1adfe4cc6566218f19970c2fd3b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/febc9a89d0d1c97b88c0f4acd32b4e67.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/791e819abbe4ecc6f2e7209839c4fc0b.png)
![](https://img.xkw.com/dksih/QBM/2021/3/28/2687822354350080/2689861230362624/STEM/604ca13a95144bf3a15f06e0a3d4008a.png?resizew=309)
![](https://img.xkw.com/dksih/QBM/2021/3/28/2687822354350080/2689861230362624/STEM/2f535de3a4d94f46999fac57388b121a.png?resizew=218)
给出下列多边形中的8个角:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a04583ebbcb5efceeb86df78ce956f3b.png)
您最近一年使用:0次