Question

Решите уравнение:
sin3x - sinx = 0

Answer 1

Решение
sin3x - sinx = 0
2sin(3x - x)/2 * cos(3x + x)/2 = 0
sinx * cos2x = 0
1) sinx = 0
x = πk, k∈Z
2)  cos2x = 0
2x = π/2 + πn, n∈z
x = π/4 + πn/2, n∈Z