Решение:
$$2 sin(x) + cos(x) - \sqrt{2} sin(x) = 0$$
$$2 sin(x) - \sqrt{2} sin(x) = - cos(x)$$
$$sin(x) (2 - \sqrt{2}) = -cos(x)$$
$$\frac{sin(x)}{cos(x)} = \frac{-1}{2 - \sqrt{2}}$$
$$tg(x) = \frac{-1}{2 - \sqrt{2}}$$
$$tg(x) = \frac{-1}{2 - \sqrt{2}} * \frac{2 + \sqrt{2}}{2 + \sqrt{2}} = \frac{-(2 + \sqrt{2})}{4 - 2} = \frac{-(2 + \sqrt{2})}{2} = -1 - \frac{\sqrt{2}}{2}$$
$$x = arctg(-1 - \frac{\sqrt{2}}{2}) + \pi n, n \in Z$$
Ответ: $$x = arctg(-1 - \frac{\sqrt{2}}{2}) + \pi n, n \in Z$$