cos(pi/2+x)=cos2x Решите уравнение, пожалуйста)

cos(pi/2+x) = -sinxcos2x= cos^2x - sin^2x-sinx = cos^2x - sin^2xcos^2x =1 - sin^2x-sinx = 1-sin^2x - sin^2x2sin^2x - sinx - 1 =0sinx = t2t^2-t-1=0D = 1 + 8 = 9t1 = 1+3/4 = 4/4 = 1t2 = -2/4 = -0.5sinx = 1x = pi/2+2pinsinx = -0.5x = -pi/6+2pinx = -5pi/6+2pin