im guessing when you say "compound" you mean Double Angle forumla? I guess in Canada they call it something different.
You have to solve the right side of the equation. 2(Sina+cosb) = (sinacosb)+(sinacosb)
then you have to simplify using the regular formulas i think
I took this a few months ago it is something like this, im sure someone else can help more. Its a start though