Find the Exact Value of Each Expression, If It Is $\cos ^ { - 1 } ( - 1 )$

Essay

Find the exact value of each expression, if it is defined.
(a) $\cos ^ { - 1 } ( - 1 )$
(b) $\sin ^ { - 1 } ( - 1 )$
(c) $\tan ^ { - 1 } ( - 1 )$