If \( \frac{\pi}{2} \leq x \leq \frac{3\pi}{4} \), then \( \cos^{-1}\!\left( \frac{12}{13}\cos x + \frac{5}{13}\sin x \right) \) is equal to:
\( x + \tan^{-1}\!\frac{4}{5} \)
\( x - \tan^{-1}\!\frac{4}{3} \)
\( x - \tan^{-1}\!\frac{5}{12} \)
\( x + \tan^{-1}\!\frac{5}{12} \)