Уравнение sin(x)+sin(3x)=0

Question

Уравнение sin(x)+sin(3x)=0

Answer 1

Sinx + sin3x = 0
2sin2x * cosx = 0

sin2x = 0 = 2x = π * n =   π * n : 2
cosx = 0 = x = +-π : 2 + πn