sin(A+B)=sinAcosB+cosAsinB
sin(A-B)=sinAcosB-cosAsinB
cos(A+B)=cosAcosB-sinAsinB
cos(A-B)=cosAcosB+sinAsinB
sin2A=2sinAcoA
cos2A=cosAcosA-sinAsinA
tan(A+B)=(tanA+tanB)/(1-tanAtanB)
tan(A-B)=(tanA-tanB)/(1+tanAtanB)
tan2A=2tanA/(1-tanAtanA)
由于平方打不出来
所以升幂降幂公式就没了