2tana=3tanb,求证tan(a-b)=sin2b/5-cos2b.

已知2tanA=tanB,求证：tan(A-B)=sin2B/(5-cos2B) 求证:tan(a+b)-tana\1+tanatan(a+b)=sin2b\2cos^2b 求证tan(A-B)=(tanA-tanB)/(1+tanAtanB) tan(a+b)=3tana 证明2sin2b-sin2a=sin(2a+2b) 已知3Sin2b=sin(2a+b)证明:tan(a+b)=2tana 已知tan(A-B)/tanA+sin^2C/sin^2A=1,求证：tanA*tanB=tan^2C tan(A+B)=tanA+tanB+tanAtanB? tan(a+b)=2/5,tan(a-b)=1/4,求tana,tanb,tan2a tan(A+B) = (tanA+tanB) / (1-tanA * tanB) = -1从而得到:tanA+tanB 已知：tan(A-B)\tanA+(sinC/sinA)*(sinC/sinA)=1,求证tanA*tanB=tanC* 证明：tan(A-B)\tanA+(sinC/sinA)*(sinC/sinA)=1,求证tanA*tanB=tanC* 已知tana+tanb=2,tan(a+b)=4.则tana*tanb