If \[ f(x) = \begin{cases} \dfrac{\sin(\cos x) - \cos x}{(\pi - 2x)^3}, & x \ne \dfrac{\pi}{2} \\ k, & x = \dfrac{\pi}{2} \end{cases} \] is continuous at \( x = \dfrac{\pi}{2} \), then \( k \) is equal to:
Evaluate the integral: \[ \int \frac{\sec^2 x}{(\sec x + \tan x)^{9/2}} \, dx \]