Question

\[\lim_{t \rightarrow \infty} \left[ \left( {-st \over s^2 + 1} - {s^2 - 1 \ \over (s^2+1)^2} \right) \cos t - \left( {t \over s^2 + 1} + {2s \over (s^2+1)^2}\right)\sin t\right]\]