Let \( x = x(y) \) be the solution of the differential equation \( y = \left(x - y \frac{dx}{dy}\right) \sin \left(\frac{x}{y}\right) \), \( y > 0 \) and \( x(1) = \frac{\pi}{2} \). Then \( \cos x(2) \) is equal to:
\( 2(\log_{e} 2)^{2} - 1 \)
\( 1 - 2 (log_{e} 2) \)
\( 1 - 2 (\log_{e} 2)^{2} \)
\( 2 (log_{e} 2) - 1 \)