How would I solve the sum and difference formula, sin and cos?

Answer 1

What do you mean by "solve"?

There are several ways to derive the sum and difference formulae for sine and cosine, i.e.

sin(x+y) etc; perhaps the neatest of these, at a reasonably elementary level, is by Ptolomy's theorem.

If you can provide more details, I can probably help you further.

P.S.

I misspelled Ptolemy..sorry about that!