This question is about pairs of functions f and g that satisfy
$$\begin{aligned}
f ( x ) - g ( x ) & = 2 \sin x \\
f ( x ) g ( x ) & = \cos ^ { 2 } x
\end{aligned}$$
for all real numbers $x$.
Across all solutions for $\mathrm { f } ( x )$, what is the minimum value that $\mathrm { f } ( x )$ attains for any $x$ ?