The functions $f$ and $g$ are given by $f ( x ) = \int _ { 0 } ^ { 3 x } \sqrt { 4 + t ^ { 2 } } d t$ and $g ( x ) = f ( \sin x )$.
(a) Find $f ^ { \prime } ( x )$ and $g ^ { \prime } ( x )$.
(b) Write an equation for the line tangent to the graph of $y = g ( x )$ at $x = \pi$.
(c) Write, but do not evaluate, an integral expression that represents the maximum value of $g$ on the interval $0 \leq x \leq \pi$. Justify your answer.