诱导公式cos(90°+B)=-sinB高中数学cos函数公式大全表，sin(90°+B)=-cosBcos(90°-B)=sinB，sin(90°-B)=cosB，tan(90°+B)=-cotB, tan(90°-B)=cotBcos(180°+B)=-cosB，sin(180°+B)=-sinBcos(180°-B)=-cosB，sin(180°-B)=-sinB，tan(180°+B)=tanB,tan(180°-B)=-tanBcos(A+B)=cosAcosB-sinAsinBcos(A-B)=cosAcosB+sinAsinBsin(A+B)=sinAcosB+cosAsinBsin(A-B)=sinAcosB-cosAsinBtan(A+B)=(tanA+tanB)/(1-tanAtanB)tan(A-B)=(tanA-tanB)/(1+tanAtanB)cos2A=cos2A-sin2A=2cos2A-1=1-2sin2Asin2A=2sinAcosAsinA=2tanA/2/(tan2A/2+1)cosA=(1-tan2A/2)/(tan2A/2+1)