= Sin² a + Cos² a -2Cos²a = Sin² a - Cos² a = -(Cos² a - Sin² a) = - Cos2a
4m+3m-2m-2p+3p-4p+3q+2q+4q=
6m-3p+9p
V3sinx-cosx=2cos3x делим на 2 всё уравнение v3/2sinx-1/2cosx=cox3x
1/2=sinpi/6 v3/2=cospi/6 =>sinxcospi/6-cosxsinpi/6=cos3x sin(x-pi/6)=cos3x
cos(pi/2-x+pi/6)=cos3x cos(4pi/6-x)=cos3x 4pi/6-x=3x 4x=4pi/6 x=pi/6+2pin