021.16. a) arccos(-\(\frac{1}{2}\)) + arcsin(-\(\frac{1}{2}\)); б) arccos(-\(\frac{\sqrt{2}}{2}\)) - arcsin(-1);

a) arccos(-\(\frac{1}{2}\)) + arcsin(-\(\frac{1}{2}\)) = \(\frac{2\pi}{3} + (-\frac{\pi}{6}) = \frac{4\pi}{6} - \frac{\pi}{6} = \frac{3\pi}{6} = \frac{\pi}{2}\) или 120° + (-30°) = 90°. б) arccos(-\(\frac{\sqrt{2}}{2}\)) - arcsin(-1) = \(\frac{3\pi}{4} - (-\frac{\pi}{2}) = \frac{3\pi}{4} + \frac{2\pi}{4} = \frac{5\pi}{4}\) или 135° - (-90°) = 225°.