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=2SinACosA Cos2A = Cos2A-Sin2A=2Cos2A-1=1-2sin2A三倍角公式sin3A = 3sinA-4(sinA)3 cos3A = 4(cosA)3-3cosAtan3a = tanatan(+a)tan(-a)半角公式sin()= cos()= tan()= cot()= tan()=和差化积 sina+sinb=2sincos sina-sinb=2cossincosa+cosb = 2coscos cosa-cosb = -2sinsintanA+tanB=sin(A+B)/c
