浙江专用2020版高考数学新增分大一轮复习第五章三角函数解三角形5.4简单的三角恒等变换第1课时课件.ppt

5.4简单的三角恒等变换,第五章三角函数、解三角形,NEIRONGSUOYIN,内容索引,基础知识自主学习,题型分类深度剖析,课时作业,1,基础知识自主学习,PARTONE,知识梳理,1.两角和与差的余弦、正弦、正切公式,ZHISHISHULI,coscossinsin,sincoscossin,sincoscossin,cos()coscossinsin(C()cos()(C()sin()(S()sin()(S(),2.二倍角公式,sin2；cos2；tan2.,2sincos,12sin2,cos2sin2,2cos21,1.诱导公式与两角和差的三角函数公式有何关系？,【概念方法微思考】,提示诱导公式可以看成和差公式中k(kZ)时的特殊情形.,2.怎样研究形如f(x)asinxbcosx函数的性质？,提示先根据辅助角公式asinxbcosxsin(x)，将f(x)化成f(x)Asin(x)k的形式，再结合图象研究函数的性质.,基础自测,JICHUZICE,题组一思考辨析1.判断下列结论是否正确(请在括号中打“”或“”)(1)存在实数，使等式sin()sinsin成立.(),1,2,3,4,5,6,7,8,题组二教材改编,1,2,3,4,5,6,7,8,1,2,3,4,5,6,7,3.P131T5sin347cos148sin77cos58.,解析sin347cos148sin77cos58sin(27077)cos(9058)sin77cos58(cos77)(sin58)sin77cos58sin58cos77cos58sin77,8,4.P146A组T4(2)tan10tan50tan10tan50.,1,2,3,4,5,6,7,8,题组三易错自纠,1,2,3,4,5,6,7,8,1,2,3,4,5,6,7,8,1,2,3,4,5,6,7,8,1,2,3,4,5,6,7,8,1,2,3,4,5,6,7,8,1,2,3,4,5,6,7,4sin,8,2,题型分类深度剖析,PARTTWO,第1课时两角和与差的正弦、余弦和正切公式,题型一和差公式的直接应用,自主演练,解析sin215cos215(cos215sin215),(1)使用两角和与差的三角函数公式，首先要记住公式的结构特征.(2)使用公式求值，应先求出相关角的函数值，再代入公式求值.,题型二和差公式的灵活应用,多维探究,命题点1角的变换,于是coscos()cos()cossin()sin,命题点2三角函数式的变换,命题点3公式的逆用与变形,得sin22sincoscos2sin22sincoscos2(sin2cos2)(cos2sin2)2(sincossincos)112sin(),(1)解决三角函数的求值问题的关键是把“所求角”用“已知角”表示.当“已知角”有两个时，“所求角”一般表示为两个“已知角”的和或差的形式；当“已知角”有一个时，此时应着眼于“所求角”与“已知角”的和或差的关系.,sinsin()sin()coscos()sin,思想方法,SIXIANGFANGFA,用联系的观点进行三角变换,三角变换的关键是找到条件和结论中的角和式子结构之间的联系.变换中可以通过适当地拆角、凑角或对式子整体变形达到目的.,例(1)(2018绍兴一中期中)(1tan21)(1tan20)(1tan25)(1tan24)的值为A.2B.4C.8D.16,解析(1tan21)(1tan20)(1tan25)(1tan24)1tan(4524)(1tan24)1tan(4525)(1tan25),cossin，,3,课时作业,PARTTHREE,基础保分练,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,A.abcB.bacC.cabD.acb,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,解析asin40cos127cos40sin127sin(40127)sin167sin13，,sin(5645)sin11，,sin13sin12sin11，acb.,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,所以cos()cos2()cos2cos()sin2sin(),1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,技能提升练,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,拓展冲刺练,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,1,2,3,4,5,6,7,8,9