三角函数公式两角和公式sin(A+B) = sinAcosB+cosAsinB sin(A-B) = sinAcosB-cosAsinB cos(A+B) = cosAcosB-sinAsinB cos(A-B) = cosAcosB+sinAsinB tan(A+B) =tan(A-B) =cot(A+B) =cot(A-B) =倍角公式tan2A =Sin2A=2SinA CosA•Cos2A = Cos2A-Sin2A=2Cos2A-1=1-2sin2A三倍角公式sin3A = 3sinA-4(sinA)3cos3A = 4(cosA)3-3cosAtan3a = tana·tan( +a)·tan(-a)半角公式sin( )=cos( )=tan( )=cot( )= tan( )==和差化积 sina+sinb=2sincossina-sinb=2cossincosa+cosb = 2coscoscosa-cosb = -2sinsintana+tanb=积化和差 sinasinb = - [cos(a+b)-cos(a-b)]cosacosb = [cos(a+b)+cos(a-b)]sinacosb = [sin(a+b)+sin(a-b)]cosasinb = [sin(a+b)-sin(a-b)]诱导公式 sin(-a) = -sina cos(-a) = cosasin( -a) = cosa cos( -a) = sinasin( +a) = cosa cos( +a) = -sinasin(π-a) = sina cos(π-a) = -cosasin(π+a) = -sina cos(π+a) = -cosatgA=tanA =万能公式sina=cosa=tana=其它公式a sina+b cosa=••×sin(a+c) [其中 tanc= ]a