Решите уравнение \(\ctg (x + \frac{\pi}{7}) = 1\) .

• \(\frac{3\pi}{28} + \pi k, k \in Z\)
• \(\frac{3\pi}{28} + 2\pi k, k \in Z\)
• \(\frac{\pi}{4} + \pi k, k \in Z\)
• \(\frac{11\pi}{28} + \pi k, k \in Z\)