Помогите решить тригонометрию

А)

cos3x (cos3x - cos5x) = 0

cos3x · ( - 2) · sin4x · sin (-x) = 0

cos3x · sin4x · sinx = 0

cos3x = 0 или sin4x = 0 или sinx = 0

3x = π/2 + πn 4x = πk x = πm

x = π/6 + πn/3 x = πk/4

б) sin5x (sinx - sin5x) = 0

sin5x · 2 · sin (-2x) · cos3x = 0

sin5x · sin2x · cos3x = 0

cos3x = 0 или sin2x = 0 или sin5x = 0

3x = π/2 + πn 2x = πk 5x = πm

x = π/6 + πn/3 x = πk/2 x = πm/5