3sin^2x - 4sinxcosx + 5cos^2x = 2*13sin^2x - 4sinxcosx + 5cos^2x = 2*(sin^2x+cos^2x)3sin^2x - 4sinxcosx + 5cos^2x = 2sin^2x + 2cos^2x3sin^2x - 2sin^2x - 4sinx*cosx + 5cos^2x - 2cos^2x = 0 sin^2x - 4sinx*cosx + 3cos^2x = 0 // : cos^2x ≠ 0 tg^2x - 4tgx + 3 = 0 (tgx - 3) (tgx - 1) = 0 tgx = 3 x = arctg(3) + pik, k ∈Ztgx = 1 x = pi/4 + pik, k ∈Z