Is this correct?
Yup. It's correct.
Sir,actually in the solution it is -3 so just clarified tysm.
There's a mistake. Differentiation of sinx is cosx not -cosx.
Yes sir tysm i had integration in my mind..
As tiklu pointed out, differentiation of sinx if cosx.
You should check your steps once and try to find out your own mistakes, it will help in long run
you have written du= -cost dt it should be du= cost dt cause differentiation of Sint is just cost not -cost