Determine the order and degree (if defined) for the differential equation (d2y/dx2) +cos(dy/dx) =0

order= 2, degree= 2. order= 2, degree= 1. order=2, degree= not defined. None of these.

order=2, degree= not defined.

The highest order derivative present in the equation is d2y/dx2. Therefore its order is 2. The given differential equation is  not a polynomial equation in its derivatives. Hence it's degree is not defined.