求证;1-2sin Xcos X/cos2 X-sin2 X=1-tan X/1+tan X
求证:(1)(sin2α - cos2α)的平方=1 - sin4α (2) tan(x/2 + π/4)+tan(x/
求证 (1—tan^2X)/(1+tan^2X)=cos^2X—sin^2X
证明(1-2sin x cos x )/(cos^2x-sin^2x)=(1-tan x)/(1+tan x)
证明1-tan^2x/1+tan^2x=cos^2x-sin^2x
证明下列恒等式:(1)(cos2α-1)/sin2α=-tanα;(2)(sinxcosx)/(sin^2x-cos^2
证明 (tan xsin x)/(tan x-sin x)-(1+cos x)/sin x
已知sin(x+y)=1,求证:tan(2x+y)+tany=0
已知sin(x+y)=1,求证:tan(2x+3y)=tany
已知sin(x+y)=1,求证:tan(2x+y)+tany=0
求证 sin^2x/(sinx-cosx)-(sinx+cosx)/tan^2 x-1=sinx+cosx
求证 sinˇ4X+sin²Xcos²X+cos²X = 1
化简(sin^2 x/sin x-cosx)-(sin x+cosx/tan^2 x-1)