证明:sin^2x+cos^2x=1
证明(1-2sin x cos x )/(cos^2x-sin^2x)=(1-tan x)/(1+tan x)
证明sin^2(x)+cos^2(x+30)+sin(x)cos(x+30)=3/4
证明成立:[cos(3x)-sin(3x)]/(cosx+sinx)=1-2sin(2x).
证明COS(X+Y)COS(X-Y)=COS^2X-SIN^2Y
证明1-tan^2x/1+tan^2x=cos^2x-sin^2x
证明下列恒等式: (1)2sin(2/π+x)cos(2/π-x)*cosθ+(2cos^2x-1)*sinθ=sin(
证明1/sin^x+1/cos^2x-1/tanx^2x=2+tan^2
证明sin4次方x+cos四次方x=1-2sin²xcos²x
证明等式:[cos(3x)-sin(3x)]/(cosx+sinx)=1-2sin(2x).成立
证明sin四次方x+cos四次方x=1-2sin平方xcos平方x
证明:(1+2sinXcosX)/(sin^2X-cos^2X)=(tanX+1)/(tanX-1)
怎么证明(1/2)sinx=sin(x/2)cos(x/2)