名校
解题方法
1 . 下列命题正确的是( )
A.与平面内无数条直线垂直的直线与该平面垂直 |
B.过直线外一点可以作无数条直线与该直线平行 |
C.正四面体的外接球球心和内切球球心恰好重合 |
D.各面都是等腰三角形的三棱锥一定是正三棱锥 |
您最近一年使用:0次
2021-10-07更新
|
859次组卷
|
3卷引用:重庆市渝北中学2024届高三上学期7月月考数学试题
名校
解题方法
2 . 为了求一个棱长为
的正四面体的体积,某同学设计如下解法.
解:构造一个棱长为1的正方体,如图1:则四面体
为棱长是
的正四面体,且有
.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/6/16/6db5d8bf-a942-4eb1-b74e-0d41be5b6734.png?resizew=583)
(1)类似此解法,如图2,一个相对棱长都相等的四面体,其三组棱长分别为
,
,
,求此四面体的体积;
(2)对棱分别相等的四面体
中,
,
,
.求证:这个四面体的四个面都是锐角三角形;
(3)有4条长为2的线段和2条长为
的线段,用这6条线段作为棱且长度为
的线段不相邻,构成一个三棱锥,问
为何值时,构成三棱锥体积最大,最大值为多少?
[参考公式:三元均值不等式
及变形
,当且仅当
时取得等号]
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cf298f00799cbf34b4db26f5f63af92f.png)
解:构造一个棱长为1的正方体,如图1:则四面体
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/68ac02c2f91cadb1e328bc6ab9b9c491.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cf298f00799cbf34b4db26f5f63af92f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f6f878ffcff2ca25a434cbeea7d5c841.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/6/16/6db5d8bf-a942-4eb1-b74e-0d41be5b6734.png?resizew=583)
(1)类似此解法,如图2,一个相对棱长都相等的四面体,其三组棱长分别为
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2967337e3fcb228dded64ab0c41a17e0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/50690dab38f4512eb72e18b7f86cf6f6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d4056761b8f826eeb6ad8c9a151d3c9c.png)
(2)对棱分别相等的四面体
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c220eadc312101e2fb89dfe920f7b30d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7de966c316db1013defc56372fcf814e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e8d2530e7023b2345c651e8f53629ff1.png)
(3)有4条长为2的线段和2条长为
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/294f5ba74cdf695fc9a8a8e52f421328.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/294f5ba74cdf695fc9a8a8e52f421328.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/294f5ba74cdf695fc9a8a8e52f421328.png)
[参考公式:三元均值不等式
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1ffb6b373d2e672bb2afc8de547861a2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4849ff71159df2bb9099b26065d81e1f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/44acc0ee22dc4b7750e8be825e7c1355.png)
您最近一年使用:0次
2021-07-15更新
|
814次组卷
|
2卷引用:重庆市西南大学附属中学2020-2021学年高一下学期期末数学试题
名校
解题方法
3 . 设
为某正方体的一条体对角线,
为该正方体的各顶点与各棱中点所构成的点集,若从
中任选两点连成线段,则与
垂直的线段数目是( )
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0f85fca60a11e1af2bf50138d0e3fe62.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cf231f8f86fb922df4ca0c87f044cec3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cf231f8f86fb922df4ca0c87f044cec3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0f85fca60a11e1af2bf50138d0e3fe62.png)
A.12 | B.21 | C.27 | D.33 |
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2024-05-31更新
|
345次组卷
|
2卷引用:重庆市重庆乌江新高考协作体2024届高三下学期模拟监测(三)数学试题
名校
解题方法
4 . 已知四边形
中,
,
,
,沿
折起使其成为大小为
(
)的二面角
.空间中一点
满足
.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/1/14/25fffed1-7342-4853-8882-cc66e2b3fb92.png?resizew=172)
(1)求证:
;
(2)若
,(即
为四面体
的外接球球心)若要使得两个三棱锥
,
拼成的多面体体积是四面体
体积的1.5倍,求
的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a65d5853c26657db448af610ac72cca4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c263c197f83830c7d48902a1b950262a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/714cc3707bba3bfdb56e251999be8592.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d40b319212a7e7528b053e1c7097e966.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c24095e409b025db711f14be783a406c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7921850f851a751f88df8f298a266705.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5f1854ba6cc92481d7a616bd2788a47e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/32d0710321d97361e5782124bbf7f0c9.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/1/14/25fffed1-7342-4853-8882-cc66e2b3fb92.png?resizew=172)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8e5ea309886e947ea7cb4b81716206fd.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0787786d1feda404b887d87d655b1a3c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/891579e7c231584a8e16b8eeff79888e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ddfe0ccf24d760c77535a70c92dad145.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08a9ec3b527947cad9caa4537e0cb7e7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/891579e7c231584a8e16b8eeff79888e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c24095e409b025db711f14be783a406c.png)
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名校
解题方法
5 . 如图,二面角
的大小为
,半径为2的球O与平面
相切于点A,与
相交于圆
,
为圆
的一条直径,
,
.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/2/1/2fad8040-b182-4cf6-bf2a-28c69631c26e.png?resizew=336)
(1)证明:
平面
;
(2)过球心的平面截球面所得圆称为大圆,如圆O,不过球心的平面截球面所得的圆为小圆,如圆
,过某两点的大圆上两点间的劣弧的长度叫这两点的球面距离,球面距离是球面上两点间距离的最小值.试求A、B两点间的球面距离.(如果某个
)满足
,则可将
记作
)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bec3143f08cc5c757ff8fb16a2d7b9bf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9f785147690f83dcee0a0bc6c327e75a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e170f206fdbbd834aad7580c727e2cc6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5b5858ee1ce52b251816757257a11c29.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/23f919bd3dde10dbbc076f7ec5149699.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/23f919bd3dde10dbbc076f7ec5149699.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/047dc9795efa99b6fb9fdf9778085dab.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cdc11a059f6073ebacd015763cdd06ea.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/2/1/2fad8040-b182-4cf6-bf2a-28c69631c26e.png?resizew=336)
(1)证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/93cf663ee2bf1ac5c43f4306fa0cf250.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c185c12f0e23a41ad82eb4c895cbb341.png)
(2)过球心的平面截球面所得圆称为大圆,如圆O,不过球心的平面截球面所得的圆为小圆,如圆
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/23f919bd3dde10dbbc076f7ec5149699.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/12f102439ebd1efd422f04209ecec2bf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8e90285b4943db2befa410d4bcec380c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e170f206fdbbd834aad7580c727e2cc6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4429c0a0cc9ee3e97ae68f28829635fc.png)
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6 . 如图,ACDE为菱形,
,
,平面
平面ABC,点F在AB上,且
,M,N分别在直线CD,AB上.
平面ACDE;
(2)把与两条异面直线都垂直且相交的直线叫做这两条异面直线的公垂线,若
,MN为直线CD,AB的公垂线,求
的值;
(3)记直线BE与平面ABC所成角为
,若
,求平面BCD与平面CFD所成角余弦值的范围.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/209acf15985d1ea1ad86fc4a37e38c0b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a1be17e0a3e51cde1f50f384198e71e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8c99e6d75d606b5cae9392ecca969200.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/84f31a3724c639f88486f8356ca65397.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac0b72906641ed13716cfbce50923282.png)
(2)把与两条异面直线都垂直且相交的直线叫做这两条异面直线的公垂线,若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3177a657a66974f53b49dc827b78c5c7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4e66082fe6f392885b1e57db9ffb5602.png)
(3)记直线BE与平面ABC所成角为
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e170f206fdbbd834aad7580c727e2cc6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5e46b60660836022a46da90173c8ef2e.png)
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7 . 如图所示的几何体是一个半圆柱和一个三棱锥的组合体.
是半圆柱的母线,
分别是底面直径BC和
的中点,
是半圆
上一动点,
是半圆
上的动点,
是圆柱的母线,延长
至
点使得
为
的中点,连接
,
构成三棱锥
.
;
(2)当三棱锥
的体积最大时,求平面
与平面
的夹角.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8ebf67d880172b27fefacc3c5b808eae.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a4d6cde991efd85f03f8801e745127a6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/56f7ba05c54b3de1f4378f7c8eb58328.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/683e17492ad37eeab880209057cb0feb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a18722354086c42e62334983fc50eb6a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/23f919bd3dde10dbbc076f7ec5149699.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2777840758e70e7dbbc18cef8f3d6d2b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4a696a182fff038a86b2bbe8ca099442.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7d0ff310aabd2282b539537ebed3f788.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/30513ea48bc1ef3ae78adac83d894f14.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d4d260c4df7b0dc180af6980d21f3371.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63397cda22cb1fad59cf966dfb588643.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cf5ae8d145c5ce43e4cfc95fe6f563ed.png)
(2)当三棱锥
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63397cda22cb1fad59cf966dfb588643.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e367b683581c7cbe018078168f69efc5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6b36a70bc52a720ba8750aee4924307.png)
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