Let
\[
f(x) =
\begin{cases}
\frac{1 - \sin^3 x}{3 \cos^2 x}, & x<\frac{\pi}{2} \\
\alpha, & x = \frac{\pi}{2} \\
\frac{\beta(1 - \sin x)}{(\pi - 2x)^2}, & x>\frac{\pi}{2}
\end{cases}
\]
If \( f(x) \) is continuous at \( x = \frac{\pi}{2} \), find \( \alpha \beta \).