[tex]sin(30^{o}) = \frac{1}{2} \\ \\ sin(-30^{o}) = -\frac{1}{2} \\ \\ arcsin( -\frac{1}{2}) = -30^{o} \\ \\ cos(60^{o})=\frac{1}{2} \\ \\ arccos( \frac{1}{2})=60^{o} \\ \\ =>arcsin( -\frac{1}{2})+arccos( \frac{1}{2})=-30^{o}+60^{o}=30^{o}= \frac{\pi}{6} [/tex]