sin(5x) = sin(9x) 5x = 9x + 2πk --> x = πk/2 5x = π - 9x + 2πk --> x = π/14 + πk/7 Ответ: {πk/2; π/14 + πk/7\ k - целое}.
Наверно х=0, х=1, х=1/2