Cos 2 2pi 3 x. Cos(3pi/2+x). Sin2x cos 3pi/2+x. 2 Cos^2 x (Pi/2 + x) корень из 3 sin. Cos 3пи/2+x. Cos6x=cos4x. Cos6x+2cos2x 0. 1 + Cos8x = 2cos4x. Cos2x+cos4x+cos6x+cos8x -0.5. (3sin(x-\Pi )-cos((\Pi )/(2)+x))/(sin(x-\Pi )). Sinx+Pi/2. Cos 3pi/2-2x. Cos(x+Pi*n) формулы