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•cosAcos2A = 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()==诱导公式 sin(-a) = -sinacos(-a) = cosasin(-a) = cosacos(-a) = sinasin(+a) = cosacos(+a) = -sinasin(π-a) = sinacos(π-a) = -cosasin(π+a) = -sinacos(π+a) = -cosatanA =万能公式sina=cosa=tana=其它公式a sina+b cosa=••×sin(a+c) [其中 tanc=]a sin(a)-b cos(a) = ••×cos(a-c) [其中 tan(c)=]1+sin(a) =(sin+cos)21-sin(a) = (sin-cos)2其他非重点三角函数csc(a) = sec(a) =双曲函数sinh(a)=cosh(a)=tg h(a)=公式一: 设 α 为任意角,终边相同的角的同一三角函数的值相等: sin(2kπ+α)= sinα cos(2kπ+α)= cosα tan(2kπ+α)= tanα cot(2kπ+α)= co