sin(2x)+cos(2x)=?
已知tan=2,求(cos x+sin x)/(cos x-sin x)+sin^2x
求导f(x) = cos(3x) * cos(2x) + sin(3x) * sin(2x).
化简y=sin^2(x)+2sin(x)cos(x)+3cos^2(x)
证明sin^2(x)+cos^2(x+30)+sin(x)cos(x+30)=3/4
求证(cos^2 x-sin^2 x)(cos^4 x+sin^4 x)+1/4 sin 2x sin 4x=cos 2
sin(x+y)sin(x-y)=k,求cos^2x-cos^2y
sin^2x+cos^2x)(sin^4x-sin^2xcos^2x+cos^4x) =sin^4x-sin^2xcos
证明(1-2sin x cos x )/(cos^2x-sin^2x)=(1-tan x)/(1+tan x)
sin(x+△x)-sinx=2sin△x/2.cos(x+△x/2)
证明COS(X+Y)COS(X-Y)=COS^2X-SIN^2Y
cos 2x /sin^2 x*cos^2 x不定积分
2cos x (sin x -cos x)+1