1 - (cos^2x - sin^2x) - 2sinxcosx = 0
cos^2x + sin^2x - cos^2x + sin^2x - 2sinxcosx = 0
2sin^2x - 2sinxcosx = 0 /:2
sin^2x - sinxcosx = 0
sinx (sinx - cosx ) = 0
1) sinx = 0
x = pik, k ∈Z
2) sinx - cosx = 0 /:cosx ≠ 0
tgx - 1 = 0
tgx = 1
x = pi/4 + pi/k, k ∈Z
Ответ
pik, k ∈Z
pi/4 + pi/k, k ∈Z