 Hello and welcome to the session. My name is Mansi and I'm going to help you with the following question. The question says find the derivative of the following functions. The first one is sin x cos x. So let's start with the solution to this question. First of all in this question we use product rule that says that d by dx of fx into gx is equal to d by dx of fx into gx plus fx into d by dx of gx. So now we put fx to be equal to sin x and gx to be equal to cos x. By doing this we get d by dx of sin x cos x is equal to d by dx of sin x into cos x plus sin x into d by dx of cos x which is equal to now derivative with respect to x of sin x is cos x into cos x plus sin x into d by dx of cos x that is minus sin x. So we have cos square x minus sin square x and this is the identity for cos 2x because cos square x minus sin square x is cos 2x. So our answer to this question is cos 2x. I hope that you understood the question and enjoyed the session. Have a good day.