正弦定理 a.doc

正弦定理 a/sinA=b/sinB=c/sinC=2R 注： 其中 R 表示三角形的外接圆半径 余弦定理 b2=a2+c2-2accosB 注：角B是边a和边c的夹角 圆的标准方程 (x-a)2+(y-b)2=r2 注：（a,b）是圆心坐标 圆的一般方程 x2+y2+Dx+Ey+F=0 注：D2+E2-4F0 抛物线标准方程 y2=2px y2=-2px x2=2py x2=-2py 直棱柱侧面积 S=c*h 斜棱柱侧面积 S=c*h 正棱锥侧面积 S=1/2c*h 正棱台侧面积 S=1/2(c+c)h 圆台侧面积 S=1/2(c+c)l=pi(R+r)l 球的表面积 S=4pi*r2 圆柱侧面积 S=c*h=2pi*h 圆锥侧面积 S=1/2*c*l=pi*r*l 弧长公式 l=a*r a是圆心角的弧度数r 0 扇形面积公式 s=1/2*l*r 锥体体积公式 V=1/3*S*H 圆锥体体积公式 V=1/3*pi*r2h 斜棱柱体积 V=SL 注：其中,S是直截面面积， L是侧棱长 柱体体积公式 V=s*h 圆柱体 V=pi*r2h 两角和公式 sin(A+B)=sinAcosB+cosAsinB sin(A-B)=sinAcosB-sinBcosA cos(A+B)=cosAcosB-sinAsinB cos(A-B)=cosAcosB+sinAsinB tan(A+B)=(tanA+tanB)/(1-tanAtanB) tan(A-B)=(tanA-tanB)/(1+tanAtanB) ctg(A+B)=(ctgActgB-1)/(ctgB+ctgA) ctg(A-B)=(ctgActgB+1)/(ctgB-ctgA) 倍角公式 tan2A=2tanA/(1-tan2A) ctg2A=(ctg2A-1)/2ctga cos2a=cos2a-sin2a=2cos2a-1=1-2sin2a 倍角公式： sin(2)=2sincos cos(2)=cos2()-sin2()=2cos2()-1=1-2sin2() tan(2)=2tan/1-tan2() 严重影响社会秩序seriously disturb social order促进经济和社会发展to promote economic对健康有好处make for good health对健康有危害a hazard to health破坏环境、污染环境poisoning the environment环境保护protect the environment浪费时间、浪费金钱、浪费精力a waste of money,time and energy促进学习facilitating learning影响学习influnce ones study提高自身水平upgrade oneself反对disapproval赞成in favor of高考英语8分作文段首句 1. 关于人们有不同的观点。一些人认为There are different opinions among people as to _ .Some people suggest that _.2. 俗话说（常言道），它是我们前辈的经历，但是，即使在今天，它在许多场合仍然适用。There is an old saying_. Its the experience of our forefathers，however，it is correct in many cases even today. 3. 现在，它们给我们的日常生活带来了许多危害。首先，；其次，。更为糟糕的是。Today, _, which have brought a lot of harms in our daily life. First, _ Second,_. What makes things worse is that_.4. 现在，很普遍，许多人喜欢，因为，另外（而且）。Nowadays，it is common to _. Many people like _ because _. Besides，_. 5. 任何事物都是有两面性，也不例外。它既有有利的一面，也有不利的一面。Everything has two sides and _ is not an exception，it has both advantages and disadvantages. 6. 关于人们的观点各不相同，一些人认为（说），在他们看来，Peoples opinions about _ vary from person to person. Some people say that _.To them,_. 任何事物都是有两面性，也不例外。它既有有利的一面，也有不利的一面。Everything has two sides and()is not an exception，it has both advantages and disadvantages. 已成为人的关注的热门话题，特别是在年青人当中，将引发激烈的辩论。() has become a hot topic among people，especially among the young andheated debates are right on their way. 在我们的日常生活中起着越来越重要的作用它给我们带来了许多好处，但同时也引发一些严重的问题。() has been playing an increasingly important role in our day-to-day life.it has brought us a lot of benefits but has created some serious problems as well人类正面临着一个严重的问题，这个问题变得越来越严重。Man is now facing a big problem () which is becoming more and more serious.根据图表/数字/统计数字/表格中的百分比/图表/条形图/成形图可以看出。很显然，但是为什么呢？Acc