名校
解题方法
1 . 已知矩形ABCD中,
,
,
分别为
中点,
为对角线
交点,如图1所示.现将
和
剪去,并将剩下的部分按如下方式折叠:沿
将
,
折叠,并使
与
重合,
与
重合,连接
,得到由平面
,
,
,
围成的无盖几何体,如图2所示.
(1)求证:
平面
;
(2)若
为棱
上动点,求
的最小值;
(3)求此多面体体积
的最大值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fcd0ced286a0fbc7e4862f8147264277.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1ffc2817fa590affb5a760a25dc65308.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7789a500686c7a73770404ead6af0590.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6d93949d8a15aca4e79cedb978590571.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/73b3c032441543354c154ee67d744abb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3fe95f656b98b53f71a9d72bf0c9a4b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4807ca16360c0cca436e59d4be98f626.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411461db15ee8086332c531e086c40c7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/372629a8666de1e9bac3e7daadcac7b6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3a7ffcd1925a2b1259221c6a476152f7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ef4113c492885ba7c47fe42ac792578f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b90e0f35eda1a729fed485f83da5ea9d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/828628c0876b45381c9a0edeb0fec236.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/683c590673eece14fea3319c4fd5eb55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411461db15ee8086332c531e086c40c7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/73bce2ee14d4769b17c26ebca1788860.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c48d06e400aa9ee1c1e958fa8ea19730.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1220cf7442bc7658dbd74a845a62dfce.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5445e7a30a0a69c66289889341142b16.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/5/31/4f5b71c2-bf45-4761-ba79-6241e73ca430.png?resizew=395)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/93cf663ee2bf1ac5c43f4306fa0cf250.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fa16146cb21f11693feffb0876c0795b.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/828628c0876b45381c9a0edeb0fec236.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/00d4f264aff7b91d14b39abd9f3b0243.png)
(3)求此多面体体积
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/be54e84508decfcce6d2fcbe6c8c1a92.png)
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解题方法
2 . 如图,一个几何体由一个长方体
与一个半圆柱组成,且
,
分别为圆柱上下底面的直径,
,
,设
,试求:(以下结果用
表示)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/1/5/3d171e2e-d8cd-4ec2-b81e-7a82611ba2d3.png?resizew=238)
(1)该几何体的表面积与体积;
(2)从点
沿几何体表面到点
的最短距离
;
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e09725691ee7851f54c0dee86b2bf55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f66fb71b75b63594ebeeeebd1963eed5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/09d27bd71d79cb19eb554175e4ef0867.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ad1a56baf43ffdf67bc8460856e31fec.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3ba4ea8a6c50e266c8ff4eb2d4fcfae0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/294f5ba74cdf695fc9a8a8e52f421328.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/1/5/3d171e2e-d8cd-4ec2-b81e-7a82611ba2d3.png?resizew=238)
(1)该几何体的表面积与体积;
(2)从点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6795cae2df43a722e1355e9562d93c09.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c3f81f2a0196b06fc56a7e8a6463d179.png)
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解题方法
3 . 将一个边长为
的正六边形
(图
)沿
对折,形成如图
所示的五面体,其中,底面
是正方形.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/7/6/0f02daa5-242a-428e-9be1-dd001ef68e52.png?resizew=464)
(1)求五面体(图
)中
的余弦值:
(2)如图
,点
分别为棱
上的动点.
①求
周长的最大值,并说明理由;
②当
周长最大时,求平面
与平面
夹角的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/61128ab996360a038e6e64d82fcba004.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9165d9bfbb0f0d19eb482c2a4c1b29b7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bdaa19de263700a15fcf213d64a8cd57.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4cae70b8a9d2d2e96dea62c00ced04b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/61128ab996360a038e6e64d82fcba004.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ad3a079cfdcca9acdacecbf08f9f78cc.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/7/6/0f02daa5-242a-428e-9be1-dd001ef68e52.png?resizew=464)
(1)求五面体(图
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/61128ab996360a038e6e64d82fcba004.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1d3f19ab76b27b47aeaaf4a66f0e580b.png)
(2)如图
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5ca7d1107389675d32b56ec097464c14.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9c0f067a2a348ceb24a408f82992eab8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5bb025beb66dc609261deac78327954c.png)
①求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/59f3f9f4edf520ce61c8e83a2be394d6.png)
②当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/59f3f9f4edf520ce61c8e83a2be394d6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/546990b47ca3fdd5681de4749246d38e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1828e73ec5e00f95aa11ff74c703a5c1.png)
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