解题方法
1 . 若任取正方体
的12条棱中的一条棱,则这条棱所在直线平行于平面
的概率为_____________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e09725691ee7851f54c0dee86b2bf55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
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解题方法
2 . 在
中,
是边
的中点,
是边
上的动点(不与
重合),过点
作
的平行线交
于点
,将
沿
折起,点
折起后的位置记为点
,得到四棱锥
,如图所示,给出下列四个结论:正确的是_______ .
不可能为等腰三角形;
②
平面
;
③对任意点
,都有平面
;
④存在点
,使得
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a7e8a02a7f28add9b9f32e836fd8a55f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/01c74a907dda6bb7d9d56d009d9df253.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.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/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5f2ea13010e2399194be2a681310543e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/49b50357a6545cae8348e3059312f520.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/57650963051ccb44a3cfb24f08228405.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1f9596850884048064a3ec8bd48c4762.png)
②
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3f81fa367ec317fe2a30142e1c30cce7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d246f9eceab371ebf47a47c2f11a4ad.png)
③对任意点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/30802944c1ea7d005c392e9a54eabedc.png)
④存在点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/666e81326945f168fc30291f1bb2fc10.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9986e9390b44ddde72b54779f5825bb6.png)
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解题方法
3 . 在棱长均相等的四面体
中,
为棱
(不含端点)上的动点,过点
的平面
与平面
平行.若平面
与平面
,平面
的交线分别为
,则
所成角的正弦值的最大值为________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e170f206fdbbd834aad7580c727e2cc6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e7b7c83470489253394bd288d7c920df.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e170f206fdbbd834aad7580c727e2cc6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7abd284f76d9f5769bc189508ce2572b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b4eb7e9ad5486cf1c5e506b20c5469e8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/280860dd039e1305a5ccc455f63e8223.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/280860dd039e1305a5ccc455f63e8223.png)
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4 . 如图①,矩形ABCD中,
,
,E,F分别为AB,DC的中点.将四边形AEFD沿EF折起至四边形
的位置,如图②.
在平面
上的射影为
的中点,则三棱锥
的体积为________ ;
(2)当平面
与平面
垂直时,作正方体
如图③.若平面
平面
,且平面
截该正方体所得图形的面积记为
,则
的最大值为________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d2c15801fee2405573677484f5dcfa4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/09d27bd71d79cb19eb554175e4ef0867.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c6ccd49a0c3ccd22943c15ed7bf0f4c2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a18722354086c42e62334983fc50eb6a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a03952d664fba91020fc5f3bcf2f9746.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/85c4bdfb0db1e31e8459df1d15f9ab55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/945fbe95bfb4e8e37e619e2d767efef6.png)
(2)当平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c6ccd49a0c3ccd22943c15ed7bf0f4c2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a03952d664fba91020fc5f3bcf2f9746.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b0bc49d40da6aebbb370be30fa2e6c06.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/414844edd458857bdfc80bffa61cbf9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ecba239ca1f109309bf14fab784ea827.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e170f206fdbbd834aad7580c727e2cc6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cf231f8f86fb922df4ca0c87f044cec3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cf231f8f86fb922df4ca0c87f044cec3.png)
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5 . 已知正三棱柱
的所有顶点都在表面积为
的球的球面上,
,点
为棱
的中点,点
是侧面
内的一点,且
平面
,则线段
的最小值为______ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/42d3a82b8e587ee890467835bc4e854c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9eea5a7fb6fb9ebab654b7c16706c8a7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d2c15801fee2405573677484f5dcfa4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/895dc3dc3a6606ff487a4c4863e18509.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0f1f229274a6e17977cc047814212589.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e168672b47d7e64dc1b404f8882c7dcf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9ad7c84ff3f05cb53cfce047e873609e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ea848cd2aa3a464618020475097949fc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6655c413f509068d30b165f9d92bdba0.png)
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6 . 在长方体
中,
,点
为侧面
内一动点,且满足![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c407eeb34204a1df967b8fbe481cb04d.png)
平面
,则
的最小值为__________ ,此时点
到直线
的距离为__________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e09725691ee7851f54c0dee86b2bf55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/febe773ba9273dc5668bdb3fbe039695.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ab3e0dba5705e1d749cfb21ebbb2ed93.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c407eeb34204a1df967b8fbe481cb04d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/895d6f710d5f67e1d4c7408d50d77281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/da7977ab975efa6411cc17de39be70d9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c407eeb34204a1df967b8fbe481cb04d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0f1f229274a6e17977cc047814212589.png)
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解题方法
7 . 如图,已知四面体
的各条棱长均等于
分别是棱
的中点.若用一个与直线
垂直,且与四面体的每一个面都相交的平面
去截该四面体,由此得到一个多边形截面
,当截面
面积最大时,四棱锥
的体积为__________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2612d8c87010adfe87728a591b63e3a9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6d93949d8a15aca4e79cedb978590571.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/49b50357a6545cae8348e3059312f520.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e170f206fdbbd834aad7580c727e2cc6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a315e4b5963127bf8550cde03ca1966d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a315e4b5963127bf8550cde03ca1966d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9df6a9fadc944f228ec12642a194f35e.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2024/6/17/50b73dc0-268c-4c34-bdb4-8ac147cdf3e5.png?resizew=168)
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8 . (易混易错辨析题)下列命题中正确的有________
①四边形可以确定一个平面;
②若一条直线与一个平面平行,则这条直线平行于这个平面内的任意一条直线;
③若两平面平行,则一个平面内的任一直线必平行于另一个平面;
④若一条直线垂直于平面内的无数条直线,则这条直线与这个平面垂直;
⑤过直线外一点,有且只有一个平面与这条直线垂直;
⑥过直线外一点,有且只有一个平面与这条直线平行.
①四边形可以确定一个平面;
②若一条直线与一个平面平行,则这条直线平行于这个平面内的任意一条直线;
③若两平面平行,则一个平面内的任一直线必平行于另一个平面;
④若一条直线垂直于平面内的无数条直线,则这条直线与这个平面垂直;
⑤过直线外一点,有且只有一个平面与这条直线垂直;
⑥过直线外一点,有且只有一个平面与这条直线平行.
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9 . 如图,若正三棱柱
的底面边长为
,对角线
的长为
,点
为
的中点,则点
到平面
的距离为______ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/42d3a82b8e587ee890467835bc4e854c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cd3304e23f3b0f9569c4140ca89b6498.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d7f6f93171329d508d491143b9d71f7b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d07ae0b4264da6a8812454ffd2f20d94.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/97c01fdc7bc471af0b264a04aef0823e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/73845d4d663b3de0b281611fe2c762fe.png)
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10 . 在边长为2的正方体
中,E,F,G是
的中点,那么过点E,F,G的截面图形为__________ (在“三角形、四边形、五边形、六边形”中选择一个);截面图形的面积为__________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e09725691ee7851f54c0dee86b2bf55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/49cf8790068c54d8123cd2dac26506b6.png)
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