三角函数的导数公式

三角函数的导数公式

三角函数求导公式(sinx)=cosx(cosx)=-sinx(tanx)=sec2x=1+tan2x(cotx)=-csc2x(secx) =tanx·secx(cscx) =-cotx·cscx.(tanx)=(sinx/cosx)=[cosx·cosx-sinx·(-sinx)]/cos2x=sec2x两角公式(1)两角和差公式sin(x+y)=sinxcosy+sinycosxsin(x-y)=sinxcosy-sinycosxcos(x+y)=cosxcosy-sinxsinycos(x-y)=cosxcosy+sinxsinytan(x+y)=sin(x+y)/cos(x+y)=sinxcosy+sinycosx/cosxcosy-sinxsiny=tanx+tany/1-tanxtanytan(x-y)=sin(x-y)/cos(x-y)=sinxcosy-sinycosx/cosxcosy+sinxsiny=tanx-tany/1+tanxtany(2)二倍角公式sin2x=2sinxcosx推导：sin2x=sin(x+x)=sinxcosx+cosxsinx=2sinxcosxcos2x=(cosx)2-(sinx)2=2cos2x-1=1-2sin2x (sin2x+cos2x=1)推导：cos2x=cos(x+x)=cosxcosx-sinxsinx=cos2x-sin2xtan2x=sin2x/cos2x=2sinxcosx/cos2x-sin2x=2tanx/1-tan2x三倍角公式sin3x=sin(2x+x)=sin2xcosx+cos2xsinx=2sinx(1-sin2x)+(1-2sin2x)sinx=3sinx-4sin3xcos3x=cos(2x+x)=cos2xcosx-sinxsin2x=(2cos2x-1)cosx-2cosx(1-cos2x)=4cos3x-3cosxtan3x=sin3x/cos3x=tanxtan(π/3+x)tan(π/3-x)2024-08-21