化简2cos^4x-2cos^2x+1/2如题.急.

化简cos 2x cos x>-1/2 证明cos 2x cos x=1/2(cos x+cos 3x) 化简f(x)=cos(-x/2)+cos(4k+1/2-x/2) 化简1+sin x/cos x·sin2x/2cos²（π/4-x/2） 化简sin^4x+cos^2x 化简sin(x)cos(x)cos(2x) 化简sin(x)cos(x)cos(2x) sin x cos x cos 2x 化简 化简(sin^2x-cos^4x+cos^2x-sin^4x)/(sin^2x-cos^6x+cos^2x-sin^6x) 2cos x (sin x -cos x)+1 化简(sin x+cos x-1)(sin x-cos x+1)/sin 2x 求解三角函数 cos 2 X (1 - 2 sin ^2 2 X) + cos 4 X ( 1 + cos 2 X)cos 2 X (1 - 2 sin ^2 2 X) + cos 4 X ( 1 + cos 2 X) = cos 2 X cos4X (1 + cos 2 X) = cos 4 X (1 +2cos 2X) = 0 化简2cos^4x-2cos^2x+1/2如题.急. 化简y=(2cos^4x-3cos^2x+1)/cos2x 2cos(x+y)cosx-cos(2x+y)化简 cos 2x(1-2sin^2 2x) + cos 4x (1+cos 2x)= cos(-x-2π) 和cos(π-x) 化简