考研数学（2）三角函数公式

1、sin(A+B)=sinAcosB+co衡痕贤伎sAsinB sin(A-B)=sinAcosB-sinBcosAcos(A+B)=cosAcosB-sinAsinB cos(A-B)=cosAcosB+sinAsinBtan(A+B)=(tanA+tanB)/(1-tanAtanB) tan(A-B)=(tanA-tanB)/(1+tanAtanB)

2、cos2a=cos2a-sin2a=2cos2a-1=1-2sin2a

3、sinA+sinB=2sin((A+B)/2)cos((A-B)/2 cosA+cosB=2cos((A+B)/2)sin((A-B)/2)tanA+tanB=sin(A+B)/cosAcos蚱澄堆别B tanA-tanB=sin(A-B)/cosAcosB