arccos \frac{1}{2} = \frac{π}{3}
arcsin(-\frac{\sqrt{3}}{2}) = -\frac{π}{3}
2arccos\frac{1}{2} - 2arcsin(-\frac{\sqrt{3}}{2}) = 2 \cdot \frac{π}{3} - 2 \cdot (-\frac{π}{3}) = \frac{2π}{3} + \frac{2π}{3} = \frac{4π}{3}
Ответ: $$\frac{4π}{3}$$