证明tan^2-sin^2=tan^2sin^2
证明(tan^2-sin^2)cot^2=sin^2
证明:tan^2角-sin^2角=tan^2角sin^2角
证明tan^2x-sin^2x=tan^2 sin^2x
证明:tan^2a-sin^2a=tan^2*sin^2a
证明tan^θ-sin^2θ=tan^2θsin^2θ
证明:(1+tan a+cot a)/(1+tan^2 a+tan a)-cot a/(1+ tan^2 a)=sin
证明tanα/2=1-cosɑ/sinɑ
证明tan a/2=sin a/(1+cos a)
证明1-tan^2x/1+tan^2x=cos^2x-sin^2x
已知tan(a+b)=2tan a 证明 3sinb=sin(2a+b)
证明恒等式:(1+sinα)/cosα=(1+tan(α/2))/(1-tan(α/2))
sin(α+β)=1 证明tan(2α+β)+tanβ =0