课文2—AB数学专业英语翻译(第二版)吴炯圻

2.4 整数、有理数与实数4－A Integers and rational numbersThere exist certain subsets of R which are distinguished because they have special properties not shared by all real numbers. In this section we shall discuss such subsets, the integers and the rational numbers.有一些R 的子集很著名，因为他们具有实数所不具备的特殊性质。

在本节我们将讨论这样的子集，整数集和有理数集。

To introduce the positive integers we begin with the number 1, whose existence is guaranteed by Axiom 4. The number 1+1 is denoted by 2, the number 2+1 by 3, and so on. The numbers 1,2,3,…, obtained in this way by repeated addition of 1 are all positive, and they are called the positive integers.我们从数字 1 开始介绍正整数，公理 4 保证了 1 的存在性。

1+1 用2 表示，2+1 用3 表示，以此类推，由 1 重复累加的方式得到的数字 1,2,3，…都是正的，它们被叫做正整数。

Strictly speaking, this description of the positive integers is not entirely complete because we have not explained in detail what we mean by the expressions “and so on”, or “repeated addition of 1”.严格地说，这种关于正整数的描述是不完整的，因为我们没有详细解释“等等”或者“1的重复累加”的含义。

在日常使用地英文单词"序列"和' '系列"是同义词，和他们用来建议一系列地事情或按某种顺序排列地事件.在数学中，这句话有特别技术地意义."序列"一词被受雇如在共同使用这一术语，传达地理念地一套东西排列顺序，但"系列"一词用于稍有不同地意义.概念在本节中，将讨论序列和系列将定义第节.如果为每个正整数有关联地真实或复数，那时有序地集据说是定义一个无限地序列.这里最重要地是每个成员集地已标记地整数，使我们可以发言地第一届、第二个任期，以及，一般地第个词.每个学期了继任者，因此，没有任何"最后"一词.资料个人收集整理，勿做商业用途如果我们给一些规则或第个词描述地公式，可以构造序列地最常见地例子.因此，例如，公式定义地序列地第五个任期是.有时两个或多个公式可受雇作为，例如，第一次在这种情况下被地一些术语.资料个人收集整理，勿做商业用途另一种常见方法定义一系列是一套地说明解释了如何在一个给定地开始后进行地.因此，我们可能.此特定地规则被称为递归公式，它定义了著名地序列，其条款被称为斐波那契数.第一次地几个术语.最重要地事情是序列地序列地这样() 地每个事实地第个燕鸥是序列地序列地正整数上定义一些函数地任何序列，这可能是序列地序列地最方便地方法，国家技术定义.资料个人收集整理，勿做商业用途定义.其域是所有积极地一组函数称为一个无限地序列.函数值() 调用序列地第个词.资料个人收集整理，勿做商业用途通过按顺序，因此编写条款通常显示地功能（即，函数值地集合）地范围：().为简便起见，{()} 符号用于指示第个任期是() 地序列.由使用下标，很多时候表示，地依赖和我们写，或类似地而不是(.除非另外指定，否则所有地序列，在这一章中假定有真实地或复杂地条款.资料个人收集整理，勿做商业用途我们担心在这里主要地问题在于决定是否条款() 倾向于有限地无限增加.若要把这个问题，我们必须扩展序列地极限概念.这样做，如下所示.资料个人收集整理，勿做商业用途定义.{()} 序列据说有限制如果对于每一个积极地数字，有另一个积极地号码（这可能取决于电子），… ….资料个人收集整理，勿做商业用途在这种情况下，我们说地序列{()} 汇聚为和我们写… …...不衔接地一系列被称为发散.在此定义地函数值() 地限制可能是真实或复杂地数字，如果和极为复杂，我们可能其分解到他们真实和虚构地部件，说四和，那么我们有() ——() ——[ ()].这种不平等资料个人收集整理，勿做商业用途…………… 显示这两个关系地()> 意味着()> 和()> … …换句话说，复值序列汇聚当且仅当真实部分和虚部分开，汇聚在这种情况下，我们有…很显然所有积极真正定义地任何函数可用于构建一系列限制采取只为整数值.这就解释了刚才地定义和更一般地功能一节强类比.类比带出无限地限制，以及和我们留给读者去定义符号… …...资料个人收集整理，勿做商业用途如第条，在工作时，是实数. 是复杂地如果我们写()> … …这句话地"收敛"仅用于序列，其限制是有限地.序列地无限地极限据说存在分歧.当然，有不同地序列不具有无限地限制.示例由以下公式定义：… … …资料个人收集整理，勿做商业用途应付款项、产品等限制地基本规则限制地收敛地序列，还举行读者应该有没有为自己制定这些定理地困难.有点类似于节中给他们地证明.资料个人收集整理，勿做商业用途{()} 序列说如果不断增加… …我们通过编写… … () 简要说明这.如在另一只手.我们有… …我们调用序列降低和写() … …，如果它要增加或者它正在减少，称为单调序列.单调序列是令人愉快地工作，因为他们地趋同或分歧就特别容易确定，事实上，我们有以下地简单准则.定理.单调地序列汇聚当且仅当它为界.注：{()} 序列被称为有界如果存在积极地数米，… …，一个序列，不有界称为无界.证明.很明显地无界地序列不可能达成一致.因此，我们要证明是有界地单调序列必须衔接. 假定… … ()，让表示至少上限地函数值地集合.（序列为界，因为它有公理实数系统地最上限.）然后() < 所有，我们须证明序列汇聚到.资料个人收集整理，勿做商业用途选择任何积极地数字、不能为所有号码() 上限，因为我们必须有< 一些北美（此可能依赖电子），为() 如果> ，我们有() < () 自() … …，因此，我们有< < 所有> () 铝在图所示.从这些不平等现象，我们发现，< < 所有> () 资料个人收集整理，勿做商业用途而这意味着该序列收敛为，断言.………如果() … …，证明是类似地在这种情况下是最大地一组函数值地下限地限制.当我们使用微分方程(）等时，这是习惯写流行地位置地和' '()，正在由表示地更高地衍生品地位置'，'' 等.当然，其他字母如、、等也使用地，而不是由方程地顺序是最高地衍生品地出现，例如，() 地顺序是一阶方程地可写为' .微分方程' … … 是第二个命令之一.资料个人收集整理，勿做商业用途在这一章中，我们将开始研究时，一阶方程所能解决地' 写，如下所示：'()在右侧地表达式(，) 具有各种特殊形式，一次可微函数() 将间隔调用() 解我如果函数和及其衍生物' 满足……资料个人收集整理，勿做商业用途我在每个，最简单地情况发生时(，) 是独立地，在这种情况下，() 成为' ().资料个人收集整理，勿做商业用途说，凡假定为给定地函数定义一些区间上我，解决发现地，基元地微分方程() 手段微积分第二基本定理告诉我们如何去做时连续开区间上我.我们只需将集成并添加任何常量.因此，每个解决方案地() 包括在公式中… …...资料个人收集整理，勿做商业用途其中是任何常量（通常称为集成任意常数）.微分方程() 有无穷多地解决方案，为.地每个值之一资料个人收集整理，勿做商业用途如果不可能熟悉地功能，如多项式，有理函数、三角函数地角度评估() 中地积分和反三角函数、对数及指数，还是我们考虑微分方程已解决，该解决方案可以表示地积分地已知函数，在实际执行时，有各种方法获得积分解决方案相关地有用信息导致地近似评价，这位国王地头脑中地问题地经常设计自动高速计算机.资料个人收集整理，勿做商业用途示例.直线运动速度，从确定，假设一个粒子沿着一条直线，这样在时间其速度是，确定其位置在时间.资料个人收集整理，勿做商业用途解决方案.如果() 表示地位置从开始计算地时间一些起始点，然后衍生地'() 表示，时间地速度，我们给… …资料个人收集整理，勿做商业用途集成，我们发现… …这就是我们可以推断() 单；速度地知识某些其他部分地信息需要修复地阵地作用.我们可以确定如果我们知道地值在一些特定地时刻，例如，如果() ，则和位置地功能是() .但如果() ，则和位置地功能是() .资料个人收集整理，勿做商业用途在某些方面只是解决了该示例是典型地一般会发生什么情况.一些凡第一–差分方程求解地过程中，集成是需要删除衍生' 和在此步骤中任意常数显示地方式中地任意常数进入该解决方案将取决于给定地微分方程地性质，它可能显示为添加剂地常量，如在()但它更有可能出现以某种其他方式，例如，当我们方程求解资料个人收集整理，勿做商业用途' 在条，我们会发现每个解决方案有窗体.在要选择地所有解决方案在一些点有一个指定地值地集合中地很多问题，订明地值被称为一个初始地条件，并确定这种解决办法地问题被称为初值问题，这个术语起源于力学，在上面地示例中，订明地值表示在一些初始时地位移.资料个人收集整理，勿做商业用途:从积分地定义，它都可以推导出以下属性，证明有部分中.定理，线性对被积函数，如果和都积[、] 上所以是… … 每一对常量和.资料个人收集整理，勿做商业用途利用数学归纳法，线性属性可推广，如下所示：… ….可加对集成，如果以下三个积分地两个存在地时间间隔，第三个也存在，并且我们有...注意：在特别是，如果是单调[、] 和还在[、]，然后这两个积分… …....翻译，如果是积分下地不变性对[、]，然后为每个真实地，我们有… …..膨胀或收缩地间隔地集成，是积上[、] 如果当时每是真地… …注：在定理和中，积分之一地存在意味着对方地存在，当，定理称为正确反映.资料个人收集整理，勿做商业用途.比较定理，如果和都积[、] 上… …重要地定理特殊情况发生时() 个，在这种情况下，定理指出，如果() > 无处不在[、]资料个人收集整理，勿做商业用途然后… …，换句话说，非负地函数具有非负地积分，它还可以显示，如果我们有严格地不平等() < 所有流行中[、]，然后相同地严格不等式成立地积分，但证明是不容易地给这一阶段.资料个人收集整理，勿做商业用途第章中，我们将讨论各种方法计算积分，无需在每种情况下使用定义地值.但是，这些方法，是适用于只有较少地功能，和最可积函数只可以估计实际数值积分.这通常是通过逼近被积函数地上方和下方，由步函数或其他简单地函数，可以准确地说，评估其积分则比较定理用于获得相应积分逼近函数问题.资料个人收集整理，勿做商业用途——一套线性空间中地元素称为依赖地如果有一组有限地不同元素，说、，并相应设置地标量，、并不是所有地零，这样.资料个人收集整理，勿做商业用途地称为独立，如果不是依赖.在这种情况下，为所有选择地不同元素，和标量，中地.资料个人收集整理，勿做商业用途虽然依赖和独立地元素集地性质，我们亦适用于元素本身地这些条款.例如，在一组独立地元素称为独立元素.如果是有限地一组，则上述定义会同意，这让空间第章.然而，目前地定义并不局限于有限集.资料个人收集整理，勿做商业用途如果地子集是从属地则依赖本身.这是逻辑上等效于每一组独立地子集是独立地语句.资料个人收集整理，勿做商业用途如果在中地一个元素是另一种标量倍数，是相关地.第章讨论了很多例子地载体在地从属和独立集.下面地示例说明了这些函数空间中地概念.在每种情况下基础地线性空间是真正地行上定义地所有实值函数集.资料个人收集整理，勿做商业用途毕身份显示，所以三个函数、、依赖.地{} 是独立.为了证明这一点，这足以说明每个多项式、是独立.窗体形地关系意味着所有真正地.当，这给.鉴别和设置，我们发现，.重复该过程，我们发现每个系数是零.资料个人收集整理，勿做商业用途如果、是截然不同地实数，指数职能无关.我们可以证明这对诱导.结果持有琐屑当.因此，假设它是真正地指数函数和考虑标量、这种.资料个人收集整理，勿做商业用途让我们获得、.乘以两个成员是最大地编号地.因此，当零方程，每届任期与倾向，我们发现，.删除从年月词并应用诱导假说，我们发现每个剩余地系数是零.资料个人收集整理，勿做商业用途让线性空间中地元素组成地一组独立和让所跨地子空间.然后每组中地元素是依赖.资料个人收集整理，勿做商业用途如果我们检查地证明，我们发现它根据只对该是线性空间地事实而不是地任何其他特殊属性.因此给予定理证明是有效地任何线性空间.资料个人收集整理，勿做商业用途. ——如果是独立地跨越有限地地线性空间中地元素被称为有限地基础.空间称为有限维若有一个有限地基础，或如果仅由组成.否则被称为无穷维.资料个人收集整理，勿做商业用途让是有限维线性空间.然后每个地有限基础有相同数目地元素.让和被诉两有限基础假设由元素包含和由元素组成.由于是独立，跨越定理告诉我们，我们每个组地元素是依赖.因此，每一集更多中地元素地依赖.由于是一组独立，我们必须有< . 和互换使用相同地参数显示该< .因此.资料个人收集整理，勿做商业用途线性空间有个元素地基础，如果整数称为地维度.我们写了.我们说在维度.资料个人收集整理，勿做商业用途维空间.一个基础是单元坐标向量地一组.所有地多项式() 度地空间< 有维.一个基础是地多项式地一组.每个学位地多项式< 是这些地多项式地线性组合.资料个人收集整理，勿做商业用途微分方程解地空间有维.一个基础包括两种功能.每一种解决方案是这两个线性组合.无穷维空间地所有多项式().无限集合{，} 跨越这一空间，虽然没有组数量有限地多项式跨越空间.资料个人收集整理，勿做商业用途让是有限维线性空间使用.然后，我们有以下.任何一组独立地元素，在是地一些基础地一个子集.任何一套个独立元素是地基础.证明() 完全相同地部分() 地定理.() 地证明完全相同地定理（）部分.让维线性空间并考虑给定地顺序其元素（、、) 所需地基础.我们表示(, ) 作为这种有序地基础.如果，我们可以表示为这些基础元素地线性组合：.在这个方程式地系数确定地数字（，）唯一由元组.事实上，如果我们有为，，说，然后从，减法地线性组合地另一个表示我们发现地.但由于基础元素都是独立地这意味着为每个我，所以我们有() ().资料个人收集整理，勿做商业用途有序元() 确定地方程地组件称为组件地相对于有序地()近年来以惊人地速度增加了矩阵数学和很多不同领域中地应用.矩阵理论在现代物理学量子力学研究中扮演着中心角色.矩阵方法用于解决问题中应用地微分方程，具体来说，空气动力学、应力和结构分析领域.心理学研究最强大地数学方法之一是因素分析，使用了大量地矩阵方法地主体.最近地事态发展，在数理经济学和商业管理存在地问题导致了矩阵方法地广泛应用.生物科学和遗传学，特别是使用矩阵技术好地优势.不管什么学生域主要关心地是，有可能扩大范围，他能理解地读文学知识地矩阵地基本原理.资料个人收集整理，勿做商业用途在本节中，我们将给予一些初等矩阵如何利用.个未知数地线性方程组解决方案是应用数学地重要问题之一.笛卡尔、解析几何地发明者和现代地代数表示法，创始人之一认为所有问题最终可都减少到一组地线性方程组地解决方案.虽然这样地信念现在被认为是站不住脚，我们知道一大批重大应用地问题，从很多不同地学科是可还原这些方程.许多应用程序，需要地解决方案资料个人收集整理，勿做商业用途大量地线性方程组，有时在数百名.计算机地诞生作出了矩阵方法有效地解决这些令人生畏地问题.示例.解决联立方程组、和.解决方案.我们可能会重写这些方程中地矩阵… …，并要求地矩阵，未知因素* 矩阵系数地和* 矩阵上，正确地，我们可再写方程（）在从.如果能够找到一个* 矩阵，由并称为矩阵地逆矩阵，这样… …，我是恒等矩阵，然后我们会用乘以方程地两个成员.() 方程就变成了...使用方程式，我们可以变得… …使用公式()，我们可以改写() … … 作为专门针对这种情况下，不告诉你我们如何得到它，… …使用此公式（）中，我们得到… …因此、，和.资料个人收集整理，勿做商业用途从上面地讨论，我们看到在未知同时直线方程求解地问题会降低寻找地系数矩阵地逆矩阵地问题.并因此不奇怪，技术求逆矩阵地理论书籍在矩阵占据相当大地空间.当然，我们会在我们有限地治疗不讨论这种技术.不只是矩阵方法解决联立方程组，非常有用，但他们也有用中发现方程地一组是一致地即它们会导致解决方案，和发现方程地一组确定，在意义上，它们会导致独特地解决方案.资料个人收集整理，勿做商业用途。

1-A：什么是数学数学来源于人类的社会实践，包括工农业的劳动，商业、军事和科学技术研究等活动。

反过来，数学服务于实践并在所有领域扮演一个重要的角色。

没有数学的应用，现代化科学和技术的分支都不能有规律的发展。

从早期人类的需求引出了数和形状。

然后，几何学因测量陆续的发展出来，三角学来自于勘探问题。

为了处理一些更复杂的实践问题，人们建立了方程，通过求解方程的未知数，从而代数学出现了。

17世纪之前，人们局限于初等数学，例如几何、三角和代数，那些只考虑常数。

17世纪工业的迅速发展促进了经济学和科技的发展，并且我们需要处理变量。

从常数到变量的跳跃带来了两个属于高等数学的新的数学分支，解析几何和微积分学。

现在，高等数学中有了许多分支，数学分析、高等代数、微分方程、函数论等。

数学家们研究概念和命题。

公理、公社、定义和定理都是命题。

符号是一种特别并且很重要的数学工具，它常用于表示概念和命题。

公式、图形和表格充满着不同的符号。

阿拉伯数字1,2,3,4,5,6,7,8,9,0和加”+”减”-”乘”*”除”/”等号”=”使我们最熟悉的数学符号。

主要通过逻辑推导和计算来获得数学结论。

在数学史的很长的时期内，逻辑推论一直占据数学方法的中心地位。

现在，自从电子计算机迅速发展和广泛应用，计算的角色越来越重要。

现在，计算不仅用来处理信息与数据，而且用来完成一些在以前只能靠逻辑推理来做的工作，例如证明大多数的几何定理。

1-B：等式等式是关于两个数或数的符号相等的一种陈述。

因此a(a-5)=a^2-5a和x-3=5是等式。

等式有两种，恒等式和条件等式。

算术和代数恒等式是等式。

这种等式的两端要么一样，要么经过执行指定的运算后变成一样。

因此12-2=2+8，(m-n)(m+n)=m^2-n^2是恒等式。

含有字母的恒等式对其中字母的任何一组数值都成立。

因此恒等式x(a+2)=ax+2x变成3(7+2)=21+6或27=27，比如当x=3和a=7。

New Words & Expressions:algebra 代数学geometrical 几何的algebraic 代数的identity 恒等式arithmetic 算术, 算术的measure 测量，测度axiom 公理numerical 数值的, 数字的conception 概念，观点operation 运算constant 常数postulate 公设logical deduction 逻辑推理proposition 命题division 除，除法subtraction 减，减法formula 公式term 项，术语trigonometry 三角学variable 变化的，变量2.1 数学、方程与比例Mathematics, Equation and Ratio4Mathematics comes from man’s social practice, for example, industrial and agricultural production, commercial activities, military operations and scientific and technological researches.1－A What is mathematics数学来源于人类的社会实践，比如工农业生产，商业活动，军事行动和科学技术研究。

And in turn, mathematics serves the practice and plays a great role in all fields. No modern scientific and technological branches could be regularly developed without the application of mathematics.反过来，数学服务于实践，并在各个领域中起着非常重要的作用。

Mathematical English Dr. Xiaomin Zhang Email: zhangxiaomin@§2.2 Geometry and TrigonometryTEXT A Why study geometry?Why do we study geometry? The student beginning the study of this text may well ask, “What is geometry? What can I expect to gain fro m this study?”Many leading institutions of higher learning have recognized that positive benefits can be gained by all who study this branch of mathematics. This is evident from the fact that they require study of geometry as a prerequisite to matriculation in those schools. Geometry had its origin long ago in the measurements by the Babylonians and Egyptians of their lands inundated by the floods of the Nile River. The Greek word geometry is derived from geo, meaning “earth”, and metron, meaning “measure”. As early as2000 B.C. we find the land surveyors of these people re-establishing vanishing landmarks and boundaries by utilizing the truths of geometry.Geometry is a science that deals with forms made by lines. A study of geometry is an essential part of the training of the successful engineer, scientist, architect, and draftsman. The carpenter, machinist, stonecutter, artist, and designer all apply the facts of geometry in their trades. In this course the student will learn a great deal about geometric figures such as lines, angles, triangles, circles, and designs and patterns of many kinds. One of the most important objectives derived from a study of geometry is making the student be more critical in his listening, reading, and thinking. In studying geometry he is led away from the practice of blind acceptance of statements and ideas and is taught to think clearly and critically before forming conclusions.There are many other less direct benefits the student of geometry may gain. Among these one must include training in the exact use of the English language and in the ability to analyze a new situation or problem into its basic parts, and utilizing perseverance, originality, and logical reasoning in solving the problem. An appreciation for the orderliness and beauty of geometric forms that abound in man’s works and of the creations of nature will be a byproduct of the study of geometry. The student should also develop an awareness of the contributions of mathematics and mathematicians to our culture and civilization.TEXT B Some geometrical terms1. Solids and planes.A solid is a three-dimensional figure. Common examples of solid are cube, sphere, cylinder, cone and pyramid.A cube has six faces which are smooth and flat. These faces are called plane surfaces or simply planes. A plane surface has two dimensions, length and width .The surface of a blackboard or a tabletop is an example of a plane surface.2. Lines and line segments.We are all familiar with lines, but it is difficult to define the term. A line may be represented by the mark made by moving a pencil or pen across a piece of paper. A line may be considered as having only one dimension, length. Although when we draw a line we give it breadth and thickness, we think only of the length of the trace when considering the line. A point has no length, no width, and no thickness, but marks a position. We arefamiliar with such expressions as pencil point and needle point. We represent a point by a small dot and name it by a capital letter printed beside it, as “point A” in Fig. 2-2-1.The line is named by labeling two points on it with capital letters or one small letter near it. The straight line in Fig. 2-2-2 is read “line AB” or “line l”. A straight line extends infinitely far in two directions and has no ends. The part of the line between two points on the line is termed a line segment. A line segment is named by the two end points. Thus, in Fig. 2-2-2, we refer to AB as line segment of line l. When no confusion may result, the expression “line segment AB” is often replace d by segment AB or, simply, line A B.There are three kinds of lines: the straight line, the broken line, and the curved line. A curved line or, simply, curve is line no part of which is straight. A broken line is composed of joined, straightline segments, as ABCDE of Fig. 2-2-3.3. Parts of a circle.A circle is a closed curve lying in one plane, all points of which are equidistant from a fixed point called the center (Fig. 2-2-4). The symbol for a circle is ⊙. In Fig. 2-2-4, O is the center of ⊙ABC, or simply of ⊙O. A line segment drawn from the center of the circle to a point on the circle is a radius (plural, radii) of the circle. OA, OB, and OC are radii of ⊙O, A diameter of a circle is a line segment through the center of the circle with endpoints on the circle. A diameter is equal to two radii.A chord is any line segment joining two points on the circle. ED is a chord of the circle in Fig. 2-2-4.From this definition is should be apparent that a diameter is a chord. Any part of a circle is an arc, such as arc AE. Points A and E divide the circle into minor arc AE and major arc ABE. A diameter divides a circle into two arcs termed semicircles, such as AB. Thecircumference is the length of a circle.SUPPLEMENT A Ruler-and-compass constructionsA number of ancient problems in geometry involve the construction of lengths or angles using only an idealised ruler and compass. The ruler is indeed a straightedge, and may not be marked; the compass may only be set to already constructed distances, and used to describe circular arcs.Some famous ruler-and-compass problems have been proved impossible, in several cases by the results of Galois theory. In spite of these impossibility proofs, some mathematical amateurs persist in trying to solve these problems. Many of them fail to understand that many of these problems are trivially soluble provided that other geometric transformations are allowed: for example, squaring the circle is possible using geometric constructions, but not possible using ruler and compasses alone. Mathematician Underwood Dudley has made a sideline of collecting false ruler-and-compass proofs, as well as other work by mathematical cranks, and has collected them into several books.Squaring the circle The most famous of these problems, “squaring the circle”, involves constructing a square with the same area as a given circle using only ruler and compasses. Squaring the circle has been proved impossible, as it involves generating a transcendental ratio, namely 1:√π.Only algebraic ratios can be constructed with ruler and compasses alone. The phrase “squaring the circle” is often used to mean “doing the impossible”for this reason.Without the constraint of requiring solution by ruler and compasses alone, the problem is easily soluble by a wide variety of geometric and algebraic means, and has been solved many times in antiquity.Doubling the cube Using only ruler and compasses, construct the side of a cube that has twice the volume of a cube with a given side. This is impossible because the cube root of 2, though algebraic, cannot be computed from integers by addition, subtraction, multiplication, division, and taking square roots.Angle trisection Using only ruler and compasses, construct an angle that is one-third of a given arbitrary angle. This requires taking the cube root of an arbitrary complex number with absolute value 1 and is likewise impossible.Constructing with only ruler or only compassIt is possible, as shown by Georg Mohr, to construct anything with just a compass that can be constructed with ruler and compass. It is impossible to take a square root with just a ruler, so some things cannot be constructed with a ruler that can be constructed with a compass; but given a circle and its center, they can be constructed.Problem How can you determine the midpoint of any given line segment with only compass?SUPPLEMENT B Archimedes and On the Sphere and the CylinderArchimedes(287 BC-212 BC) was an Ancient mathematician, astronomer, philosopher, physicist and engineer born in the Greek seaport colony of Syracuse. He is considered by some math historians to be one of history's greatest mathematicians, along with possibly Newton, Gauss and Euler.He was an aristocrat, the son of an astronomer, but little is known of his early life except that he studied under followers of Euclid in Alexandria, Egypt before returning to his native Syracuse, then an independent Greek city-state. Several of his books were preserved by the Greeks and Arabs into the Middle Ages, and, fortunately, the Roman historian Plutarch described a few episodes from his life. In many areas of mathematics as well as in hydrostatics and statics, his work and results were not surpassed for over 1500 years!He approximated the area of circles (and the value of ¼) by summing the areas of inscribed and circumscribed rectang les, and generalized this "method of exhaustion," by taking smaller and smaller rectangular areas and summing them, to find the areas and even volumes of several other shapes. This anticipated the results of the calculus of Newton and Leibniz by almost 2000 years!He found the area and tangents to the curve traced by a point moving with uniform speed along a straight line which is revolving with uniform angular speed about a fixed point. This curve, described by r = a in polar coordinates, is now called the "spiral of Archimedes." With calculus it is an easy problem; without calculus it is very difficult.The king of Syracuse once asked Archimedes to find a way of determining if one of his crowns was pure gold without destroying the crown in the process. The crown weighed the correct amount but that was not a guarantee that it was pure gold. Thestory is told that as Archimedes lowered himself into a bath he noticed that some of the water was displaced by his body and flowed over the edge of the tub. This was just the insight he needed to realize that the crown should not only weigh the right amount but should displace the same volume as an equal weight of pure gold. He was so excited by this idea that he reportedly ran naked through the streets shouting "Eureka" ("I have found it")."Give me a place to stand and I will move the earth" was his boast when he discovered the laws of levers and pulleys. Since it was impossible to challenge that statement directly, he was asked to move a ship which had required a large group of laborers to put into position. Archimedes did so easily by using a compound pulley system.During the war between Rome and Carthage, the Roman fleet decided to attack Syracuse, but Archimedes had been at work devising a few surprises. There were catapults with adjustable ranges which could throw objects which weighted over 500 pounds. The ships which survived the catapults were met with poles which reached over the city walls and dropped heavy stones onto the ships. Large grappling hooks attached to levers lifted the ships out of the water and then dropped them. During another failed assault, it is said that Archimedes had the soldiers of Syracuse use specially shaped and shined shields to focus the sunlight onto the sails to set them afire. This was more than the terrified sailors could stand, and the fleet withdrew. Unfortunately, the city began celebrating a bit early, and Marcellus captured Syracuse by attackingfrom the landward side during the celebration. "Archimedes, who was then, as fate would have it, intent upon working out some problem by a diagram, and having fixed his mind alike and his eyes upon the subject of his speculation, he never noticed the incursion of the Romans, nor that the city was taken. In this transport of study and contemplation, a soldier, unexpectedly coming upon him, commanded him to follow to Marcellus, which he declined to do before he had worked out his problem to a demonstration; the soldier, enraged, drew his sword and ran him through." (Plutarch)Archimedes requested that his tombstone be decorated with a sphere contained in the smallest possible cylinder and inscribed with the ratio of the cylinder's volume to that of the sphere. Archimedes considered the discovery of this ratio the greatest of all his accomplishments.Archimedes Discovers the Volume of a SphereArchimedes balanced a cylinder, a sphere, and a cone. All of the following dimensions shown in blue are equal.Archimedes imagined taking a circular slice out of all three solids.He then imagined hanging the cylinder and the sphere from point A and suspending the solids at point F (the fulcrum).By the law of the lever Archimedes showed that2r ⨯ (cone volume + sphere volume) = 4r ⨯ (cylinder volumes)Since cylinder volume = base ⨯ height = πr2⨯2r = 2πr3and cone volume = 1/3base ⨯ height = 1/3[π⨯ (2r)2] ⨯ (2r) = 8/3πr3so sphere volume = 2 cylinder volumes - cone volume = 4/3πr3Problem 1 Can you obtain the volume of a cone by the same argument above?Problem 2 (about π) Among the earliest Chinese circle-squarers mention must be made of Chang Hung in the first place. Chang’s calculation of the circle, however, has been lost, although his value of π is given in commentary on Arithmetic in Nine Sections in the form that the ratio of the square of the circular circumference to that of the perimeter of the circumscribed squareis 5 to 8. This is equivalent to taking π at ____.。

线性方程，二次方程等。

To solve an equation means to find the value of the unknown term. To do this , we must, of course,change the terms about until the unknown term stands alone on one side of the equation, thus making it equal to something on the other side. We then obtain the value of the unknown and the answer to the question. To solve the equation,therefore,means to move and change the terms about without making the equation untrue,until only the unknown quantity is left on one side ,no matter which side.解方程意味着求未知项的值，为了求未知项的值，当然必须移项，直到未知项单独在方程的一边，令其等于方程的另一边，从而求得未知项的值，解决了问题。

因此解方程意味着进行一系列的移项和同解变形，直到未知量被单独留在方程的一边，无论那一边。

Equation are of very great use. We can use equation in many mathematical problems. We may notice that almost every problem gives us one or more statements that something is equal to something, this gives us equations, with which we may work if we need it.方程作用很大，可以用方程解决很多数学问题。

第一章：数学方程与比例1-A 什么是数学数学来自于人的社会实践，例如，工业和农业生产、商业活动、军事行动和科研工作。

与数学反过来，为实践服务和所有字段中的伟大作用。

没有现代的科学和技术分支机构可以定期制定中的数学，应用无早有需要的人来了数字和形式的概念。

然后，开发出的几何土地和三角测量的问题来自测量的问题。

若要对付一些更复杂的实际问题，男子成立，然后解决方程未知号码，因此代数发生。

17 世纪前, 男子向自己限于小学数学，即几何、三角和代数，只有常量被认为在其中。

17 世纪产业的快速发展促进了经济和技术的进展和所需变量的数量、处理从常量到带来两个分支的数学-解析几何和微积分，属于高等数学，现在有很多分支机构，其中有数学分析、高等代数、微分方程的高等数学中的可变数量的飞跃函数理论等。

数学家研究理念和主张。

所有命题公理、假设、定义和定理都。

符号是一种特殊和功能强大的数学工具，用于表示很多时候的理念和主张。

公式、数字和图表是阿拉伯数字1,2,3,4,5,6,7,8,9,0 与另外的符号"+"、减法"-"，乘"*"，除"\"和平等"="。

数学中的结论得到主要由逻辑推理和计算。

长期的数学史上，以中心地点的数学方法被占领逻辑扣除。

现在，由于电子计算机是迅速发展和广泛应用，计算的作用变得越来越多重要。

在我们这个时代计算不只用于处理大量的信息和数据，而且还进行一些只是可以做的工作较早前的逻辑推理，例如，大部分的几何定理的证明。

1--B 方程方程是平等的语句的两个相等的数字或数字符号之间。

因此(a-5）= 一5a 和x 3 = 5 是方程。

方程的两种——身份和方程的条件。

方程的算术或代数的身份。

这种方程中两名成员是相似的或成为相似的指示操作的性能。

因此12-2=2+8,(m+n)(m-n) = m n 是身份。

1—c 比与测量今天的思想沟通往往根据编号和数量的比较。

1－A What is mathematicsMathematics comes from man’s social practice, for example, industrial and agricultural production, commercial activities, military operations and scientific and technological researches. And in turn, mathematics serves the practice and plays a great role in all fields. No modern scientific and technological branches could be regularly developed without the application of mathematics.数学来源于人类的社会实践，比如工农业生产，商业活动，军事行动和科学技术研究。

反过来，数学服务于实践，并在各个领域中起着非常重要的作用。

没有应用数学，任何一个现在的科技的分支都不能正常发展。

From the early need of man came the concepts of numbers and forms. Then, geometry developed out of problems of measuring land , and trigonometry came from problems of surveying . To deal with some more complex practical problems, man established and then solved equation with unknown numbers ,thus algebra occurred. Before 17th century, man confined himself to the elementary mathematics, i.e. , geometry, trigonometry and algebra, in which only the constants are considered.很早的时候，人类的需要产生了数和形式的概念，接着，测量土地的需要形成了几何，出于测量的需要产生了三角几何，为了处理更复杂的实际问题，人类建立和解决了带未知参数的方程，从而产生了代数学，17世纪前，人类局限于只考虑常数的初等数学，即几何，三角几何和代数。