2cos^2x-2sin2x+1=0.

2cos^2x-2sin2x+1=0.

2cos^2x - 4sinxcosx + 1 = 0

2cos^2x - 4 sinxcosx + sin^2x + cos^2x = 0

sin^2x - 4sinxcosx + 3cos^2x = 0 / : cos^2x не рав. 0

tg^2x - 4tgx + 3=0

(tgx - 1) (tgx - 3) = 0

1) tgx = 1 = = > x = pi/4 + pik, k c Z

2) tgx = 3 = = = > x = arctg (3) + pik, k c Z