cos(2x+60`)cos(x-30`)+sin(2x+60`)sin(x-30`)=1/2
证明sin^2(x)+cos^2(x+30)+sin(x)cos(x+30)=3/4
已知tan=2,求(cos x+sin x)/(cos x-sin x)+sin^2x
2cos x (sin x -cos x)+1
求证(cos^2 x-sin^2 x)(cos^4 x+sin^4 x)+1/4 sin 2x sin 4x=cos 2
求导f(x) = cos(3x) * cos(2x) + sin(3x) * sin(2x).
证明(1-2sin x cos x )/(cos^2x-sin^2x)=(1-tan x)/(1+tan x)
sin(45-3x)*cos(60-3x)-cos(30+3x)*sin(45+3x)
sin(45-3x)*cos(60-3x)-cos(30+3x)*sin(45+3x) ?
化简y=sin^2(x)+2sin(x)cos(x)+3cos^2(x)
化简 1/2cos x-根号3/2sin x 根3sin x+cos x
化简[1-(sin^4x-sin^2cos^2x+cos^4x)/(sin^2)]+3sin^2x
cos 2x /sin^2 x*cos^2 x不定积分