Arctg(-1/корень3)+arccos(-1/2)

[tex]arctg( \frac{-1}{ \sqrt{3} }) +arccos( \frac{-1}{2})= - \frac{ \pi }{6}+ \frac{2 \pi }{3}= \frac{-\pi +4 \pi }{6}= \frac{3 \pi }{6}= \frac{\pi }{2} [/tex]

= - pi/6 + 2pi/3 = pi/2.