L don't know how to solve it so please help me and solve it in detail so please help me to solve it ..............

I have made a mistake in calculations in last few steps in the previous answer.Here I am attaching the correct solution.

See the attachment for details solution.

In this type of questions, you should remember that the differentiation of cos is -sin and differentiation of sin is cos, then use substitution. solution attached.

8/45 is the correct answer..

here is the solution...hope this will help you....

hope it will help you.

solution: