sin^2(x) - 4sin(x)*cos(x) + 3cos^2(x) = 0

sin^2(x) - 4sin(x)*cos(x) + 4cos^2(x) - cos^2(x) = 0

[sin(x) - 2cos(x)]^2 - cos^2(x) = 0

[sin(x) - 2cos(x) - cos(x)] * [sin(x) - 2cos(x) + cos(x)] = 0

[sin(x) - 3cos(x)] * [sin(x) - cos(x)] = 0

sin(x) - 3cos(x) = 0

и

sin(x) - cos(x) = 0

tg(x) = 3; tg(x) = 1

x1 = arctg(3) +/- Pi

x2 = Pi/4 +/- Pi