в) arccos(-\(\frac{\sqrt{2}}{2}\)) + arccos(\(\frac{\sqrt{2}}{2}\)) = \(\frac{3\pi}{4} + \frac{\pi}{4} = \pi\) или 135° + 45° = 180°.
г) arccos(-\(\frac{1}{2}\)) - arccos(\(\frac{1}{2}\)) = \(\frac{2\pi}{3} - \frac{\pi}{3} = \frac{\pi}{3}\) или 120° - 60° = 60°.