(1) 两角和公式sin(A+B)=sinAcosB+cosAsinBsin(A B)=sinAcosB-sinBcosA cos(A+B)=cosAcosB-sinAsinBcos(A B)=cosAcosB+sinAsinB Tan(A+B)=(tanA +tanB)/(1-tanAtanB)tan(A·B)=(tanA-tanB)/(1+tanAtanB) ctg(A+B)=(ctgActgB-1)/(ctgB+ctgA)ctg(A·B)=(ctgActgB +1)/(ctgB-ctgA)
(2)双角公式tan2A=2tanA/(1-tan2A)ctg2A=(ctg2A 1)/2ctga cos2a=cos2a-sin2a=2cos2a-1=1-2sin2a
(3) 半角计算公式sin(A/2)=((1-cosA)/2)sin(A/2)=-((1cosA)/2) cos(A/2)=( ( 1 +cosA)/2)cos(A/2)=V((1+cosA)/2)tan(A/2)=((1-cosA)/((1+cosA))tan(A/2 )=((1-cosA)/((1+cosA)) ctg(A/2)=v((1+cosA)/((1-cosA))ctg(A/2)=( ( 1 +cosA)/((1-cosA))
(4) 和差积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)/cosAcosBtanA TanB=sin(A-B)/cosAcosB ctgA+ctgBsin(A+B)/sinAsinB ctqA+ctgBsin(A+B)/sinAsinB
(5) 积和差2sinAcosB=sin(A+B)+sin(A-B) 2cosAsinB=sin(A+B)-sin(A-B) 2cosAcosB=cos(A+B)-sin(A-B) -2sinAsinB=cos (A+B)-COS(A-B)
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