2 arcsin (-корень 3/2) + arcctg (-1) + arccos корень 2/2

Решите задачу:

$2arcsin (-\frac{\sqrt{3}}{2}) + arcctg (-1) + arccos (\frac{\sqrt{2}}{2}) =\\ 2 (-\frac{\pi}{3}) - ( \frac{\pi}{4}) + ( \frac{\pi}{4}) = -\frac{2\pi}{3}$