 Hi and welcome to the session. Let us discuss the following question. Question says the degree of the differential equation d square phi upon dx square whole cube plus square of dy upon dx plus sin dy upon dx plus 1 is equal to 0 is a3 b2 c1 d not defined. We have to choose the correct answer from a, v, c and d. Let us now start with the solution. Now first of all let us rewrite the given differential equation it is cube of d square y upon dx square plus square of dy upon dx plus sin dy upon dx plus 1 is equal to 0. Now we know degree of a differential equation is defined if it is a polynomial equation in its derivatives. Now clearly we can see this given differential equation is not a polynomial equation in its derivatives or we can say the given differential equation is not a polynomial equation in dy upon dx. Now we can write the given differential equation is not a polynomial equation in its derivatives. So its degree is not defined. So our correct answer is d. This is our required answer. This completes the session. Hope you understood the solution. Take care and keep smiling.