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解题方法
1 . 材料1.类比是获取数学知识的重要思想之一,很多优美的数学结论就是利用类比思想获得的.例如:若
,
,则
,当且仅当
时,取等号,我们称为二元均值不等式.类比二元均值不等式得到三元均值不等式:
,
,
,则
,当且仅当
时,取等号.我们经常用它们求相关代数式或几何问题的最值,某同学做下面几何问题就是用三元均值不等式圆满完成解答的.
题:将边长为
的正方形硬纸片(如图1)的四个角裁去四个相同的小正方形后,折成如图2的无盖长方体小纸盒,求纸盒容积的最大值.
,则纸盒容积
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/71c081a56a12c5d11c9b4f31008a65ec.png)
当且仅当
,即
时取等号.所以纸金的容积取得最大值
.在求
的最大值中,用均值不等式求最值时,遵循“一正二定三相等”的规则.你也可以将
变形为
求解.
你还可以设纸盒的底面边长为
,高为
,则
,则纸盒容积
.
当且仅当
,即
,
时取等号,所以纸盒的容积取得最大值
.
材料2.《数学必修二》第八章8.3节习题8.3设置了如下第4题:
如图1,圆锥的底面直径和高均为
,过
的中点
作平行于底面的截面,以该截面为底的面挖去一个圆柱,求剩下几何体的表面积和体积.我们称圆柱为圆锥的内接圆柱.
根据材料1与材料2完成下列问题.
如图2,底面直径和高均为
的圆锥有一个底面半径为
,高为
的内接圆柱.
与
的关系式;
(2)求圆柱侧面积的最大值;
(3)求圆柱体积的最大值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/94440d3e4c073f94f2b266ff99d50e74.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/67ca5fd57c2c2fcc3c7a574fdd1467d9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/689f982af451283289255c87593ec338.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1f22fec5a381ae8aca93d876e54c79de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/94440d3e4c073f94f2b266ff99d50e74.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/67ca5fd57c2c2fcc3c7a574fdd1467d9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8cec12441802f71e803efaf2c62ee588.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8d936ea1443a8c881633d5e04fdd3434.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/44acc0ee22dc4b7750e8be825e7c1355.png)
题:将边长为
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/689ff84e2d7f52c7446ef789a54557da.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e4e3c92be4b3f494e7d03c67819632c0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/71c081a56a12c5d11c9b4f31008a65ec.png)
当且仅当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/efaf86a31a17f80098a020b74d5282bc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/707ea658f3a9359f5740d5aab48f7948.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b50995580ef9cbc240041c2f8d00d79d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/be54e84508decfcce6d2fcbe6c8c1a92.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dbb2757026c0f75d4f1ea56349b177b7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ab79a858ff360048fb4f1f7784cbfe8d.png)
你还可以设纸盒的底面边长为
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2c94bb12cee76221e13f9ef955b0aab1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/493dbbbcf8aecaf1b586774ad7846f64.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/db442d96d27b4c73a3dc684756b7a0b2.png)
当且仅当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3527a89afa5fbd67781a204d3954a02e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/36e15cbd7c42d7b15d7ba8d2b28ab8df.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03837b3769eda7f0d3804cc5ad4a6d60.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b50995580ef9cbc240041c2f8d00d79d.png)
材料2.《数学必修二》第八章8.3节习题8.3设置了如下第4题:
如图1,圆锥的底面直径和高均为
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ef49a3ca580a144cc65a609c167facc1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/23f919bd3dde10dbbc076f7ec5149699.png)
根据材料1与材料2完成下列问题.
如图2,底面直径和高均为
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4dd6f4250ca6b1b9bce234a01f00d44d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4aa0df7f1e45f9de29e802c7f19a4f64.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/73465a1f9aa03481295bf6bd3c6903ac.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4aa0df7f1e45f9de29e802c7f19a4f64.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/73465a1f9aa03481295bf6bd3c6903ac.png)
(2)求圆柱侧面积的最大值;
(3)求圆柱体积的最大值.
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2 . 中国古代数学名著《九章算术•商功》中,阐述:“斜解立方,得两堵.斜解壍堵,一为鳖臑.阳马居二,鳖臑居一”,
平面ABC,
,PA=AB=BC=4,则PB与AC所成的角等于______ ;PC与AB之间的距离等于______ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ccd4fd4b7a4d6b8ca0c5827c055a9ce7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/080db3af81b29ed10144a1c2e2a4fb8a.png)
![](https://img.xkw.com/dksih/QBM/2021/10/21/2834324322140160/2834895242723328/STEM/03c7391e49664728926e4b1399819c8e.png?resizew=128)
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3 . 如图,在平行六面体
中,
,
,
.用向量法 解下列问题:
![](https://img.xkw.com/dksih/QBM/editorImg/2023/12/30/5cb11c55-bc0f-4bea-85db-1259fb30f49c.png?resizew=165)
(1)求
长度;
(2)求证:
;
(3)若点M,N分别在直线
和
上运动,当
且
时(MN为公垂线段,这样的MN只有一条),求MN的长度.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b3da8c338342e38c9aa3f274c053fd5b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/067613594cca07e73993d85045e8964f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d262480ffb55b7617f44b63f130c154a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/92535536bd3c2761724fd058427f95a8.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/12/30/5cb11c55-bc0f-4bea-85db-1259fb30f49c.png?resizew=165)
(1)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6eb97aff0960e2640314888a38e7169c.png)
(2)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b219a74a1ce5a2b22c36d8de1e21ff91.png)
(3)若点M,N分别在直线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/82b25f3ea33cc08b1e2a0d9c3a9dccaf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6eb97aff0960e2640314888a38e7169c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/df93277710b49a14d6ff1b9d5e99260c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/722ba1f4d15c9bf91ef3de85202e9406.png)
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解题方法
4 . 在长方体
中,
,
,
,
是
的中点,建立空间直角坐标系,用向量方法解下列问题:
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/18/c04c4cdd-3209-4d21-96e8-cc98097c1355.png?resizew=173)
(1)求直线
与
所成的角的余弦值;
(2)求点
到直线
的距离.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/95628327dc58037e5368f4404c05ec39.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5adf8bccbc5113a6d8f85285c6dc28cd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/368fc197b61e01fe6a4a168bb7b375cd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9a4acc5d21a7490e6bed2453cc5147c1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/18/c04c4cdd-3209-4d21-96e8-cc98097c1355.png?resizew=173)
(1)求直线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7cee51552e3c12bc27cf8ab1777bf191.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f1158eaa2e338f564eb18de5bef1d25.png)
(2)求点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/23f919bd3dde10dbbc076f7ec5149699.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
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解题方法
5 . 有一圆柱形的无盖杯子,他的内表面积是
.
(1)试用解析式将杯子的容积
表示成底面半径
的函数;
(2)定理:若
,则
,当且仅当
时等号成立.
阅读下列解题过程:求函数
的最大值.
解:
,当且仅当
,即
时等号成立,所以
时,
的最大值为
.
问:当杯子的底面半径为多少时,杯子的容积最大,最大容积是多少?
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b12d5b15f6979cd665d54fd17341fc2f.png)
(1)试用解析式将杯子的容积
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/04b785a4b6636ed1f145ed8f7e3a0fef.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5be6e964c405a9cdf6623f9219898fd3.png)
(2)定理:若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2c0c9fd7b50fc20cc3e7c0bd4442c306.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/162cd9270205b4e891f7e806abe01bf5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/44acc0ee22dc4b7750e8be825e7c1355.png)
阅读下列解题过程:求函数
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/896cf6a3fcde580b4cd78431ba255d0f.png)
解:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/68661d53ba9a388797dc9a42595a593d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/25359e135f750694a9103837dbc9a291.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/280878aa2e6d5580178cc6c99229b9ed.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/280878aa2e6d5580178cc6c99229b9ed.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d053b14c8588eee2acbbe44fc37a6886.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/738bc12c4d44438814ce6f606fda695a.png)
问:当杯子的底面半径为多少时,杯子的容积最大,最大容积是多少?
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6 . 国家主席习近平指出:中国优秀传统文化有着丰富的哲学思想、人文精神、教化思想、道德理念等,可以为人们认识和改造世界提供有益启迪.我们要善于把弘扬优秀传统文化和发展现实文化有机统一起来,在继承中发展,在发展中继承.《九章算术》作为中国古代数学专著之一,在其“商功”篇内记载:“斜解立方,得两堑堵,斜解堑堵,其一为阳马,一为鳖臑”.刘徽注解为:“此术臑者,背节也,或曰半阳马,其形有似鳖肘,故以名云”. 鳖臑,是我国古代数学对四个面均为直角三角形的四面体的统称.在四面体
中,PA⊥平面ACB.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/10/24/58c3ca96-ee25-4cb8-8cc9-cb263cb93982.png?resizew=314)
(1)如图1,若D、E分别是PC、PB边的的中点,求证:DE
平面ABC;
(2)如图2,若
,垂足为C,且
,求直线PB与平面APC所成角的大小;
(3)如图2,若平面APC⊥平面BPC,求证:四面体
为鳖臑.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/23f44cc3030c28fdf4776b1a29c5df7c.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/10/24/58c3ca96-ee25-4cb8-8cc9-cb263cb93982.png?resizew=314)
(1)如图1,若D、E分别是PC、PB边的的中点,求证:DE
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fb31ef428bd9de9bc875b343feded3c7.png)
(2)如图2,若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ef336bafe4e08c983d0286c13182d81d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f6bf93402a48635572cbaadc2513ecd5.png)
(3)如图2,若平面APC⊥平面BPC,求证:四面体
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/23f44cc3030c28fdf4776b1a29c5df7c.png)
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2022-10-20更新
|
143次组卷
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2卷引用:四川省泸州市龙马高中2022-2023学年高二上学期第一次月考数学(理)试题
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7 . 如图,正三棱柱
的所有棱长都为
,
为
中点.试用空间向量知识解下列问题:
![](https://img.xkw.com/dksih/QBM/editorImg/2023/3/2/54199679-d4fd-4b3a-bd08-5c4657b6bbb6.png?resizew=180)
(1)求证:平面
平面
;
(2)求二面角
的正弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/42d3a82b8e587ee890467835bc4e854c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/61128ab996360a038e6e64d82fcba004.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d88bf46ad08f9677c37eed1d0369329.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/3/2/54199679-d4fd-4b3a-bd08-5c4657b6bbb6.png?resizew=180)
(1)求证:平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/85a2e10a5aebe40a9018d5ee3ade7af8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7935fe3125f247b7bea4f065ce9ad985.png)
(2)求二面角
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f97babc2abb18c1540d3a5504f7cf3fe.png)
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2019-10-21更新
|
347次组卷
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2卷引用:河北省辛集中学2020届高三上学期模拟考试(一)数学(理)试卷