Sin (pi/5-4x)больше-1/2

Вот Решение sin (П/5-4x) > -1/2 sin(4x - π/5) < 1/2 - π - arcsin(1/2) + 2πn < 4x - π/5 < arcsin(1/2) + 2πn, n∈z - π - π/6 + 2πn < 4x - π/5 < π/6 + 2πn, n∈Z  - 7π/6 + 2πn < 4x - π/5 < π/6 + 2πn, n∈Z  - 7π/6 + π/5 + 2πn < 4x  < π/6 + π/5 + 2πn, n∈Z  - 29π/30 + 2πn < 4x < 11π/30 + 2πn, n∈Z  - 29π/120 + πn/2 <  x < 11π/120 +  πn/2, n∈Z