Sinx+sin2x+sin3x=cosx+cos2x+cos3x
2Sin2xCosx + Sin2x = 2Cos2xCosx + Cos2x
Sin2x(2Cosx +1) = Cos2x(2Cosx +1),
Sin2x(2Cosx +1) - Cos2x(2Cosx +1)= 0
(2Cosx +1)(Sin2x -Cos2x) = 0
2Cosx +1 = 0 или Sin2x -Cos2x = 0
Cosx = -1/2 tg2x = 1
x = +-2π/3 + 2πk , k ∈Z 2x = π/4 + πn , n ∈Z
x = π/8 + πn/2 , n∈Z