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