Yup, you're on the right track
But after the second substitution, you put a minus sign instead of + sign :
Because it's -*-
I haven't looked further, correct it and then see if it corresponds
Just when I think I have mastered reduction formulae, the "miscellaneous exercise" happens!
The question is:
My working goes like this:
I'm clearly on the right track, I just can't see what's going wrong.
Thanks to anyone who posts!