 Hello and welcome to the session. My name is Mansi and I am going to help you with the following question. The question says find an anti-derivative or integral of the following by the method of inspection cos 3x. So let us start with the solution to this question. First of all we consider d by dx of sin 3x that is equal to 3 cos 3x because derivative of sin 3x is cos 3x and derivative of 3x will get multiplied with cos 3x that is 3. This implies that cos 3x is equal to 1 by 3 into d by dx of sin 3x. This implies that cos 3x is equal to d by dx of 1 by 3 sin 3x. Since 1 by 3 is a constant so we can easily take out take it inside d by dx. Hence an anti-derivative of cos 3x is equal to 1 by 3 sin 3x. So this is our answer to the question. I hope that you understood the question and enjoyed the session. Have a good day.