Помогите, пожалуйста.
sin^2x-cos^2x=cos2x

sin^2x-cos^2x=cos2xsin^2x - cos^2x = 2cos^2x - 1sin^2x = 3cos^2x - 1sin^2x = 3cos^2x - (sin^2x + cos^2x)sin^2x = 3cos^2x - sin^2x - cos^2x2sin^2x = 2cos^2xsin^2x = cos^2x. Делим на cos^2x.tg^2x = 1tgx = +- 1Отсюда x = π/4 + (π/2) * n, n ∈ Z