$\large\frac{\cos x}{\cos (x-2y)}$$=\lambda => \tan (x-y) \tan y=$

Question

\[\begin {array} {1 1} (1)\;\frac{1+\lambda}{1-\lambda} & \quad (2)\;\frac{1-\lambda}{1+\lambda} \\ (3)\;\frac{\lambda}{1+\lambda} & \quad (4)\;\frac{\lambda}{1-\lambda} \end {array}\]