(20 points) Find the exact values of each of the following expressions involving inverse trigonometric functions. Briefly explain how you found your answers. ) arccos (-)2 \tan ^{-1}\left(\tan \left(\frac{7 \pi}{6}\right)\right)

\sin ^{-1}\left(\sin \left(\frac{15 \pi}{8}\right)\right) \tan \left(\sin ^{-1}\left(-\frac{\sqrt{5}}{3}\right)\right)