Reposting this because I think I asked in a confusing manner before. Im using sum & Difference identities will post more in the response because I cant figure out how to put the proper symbols in here lmfao.

Question

anonymous · Answer

Problem= $$\cos (11\pi \div 12)$$

should I use $$\cos (\alpha-\beta) = \cos(\alpha)\cos (\beta) +\sin (\alpha) \sin(\beta) $$

Im assuming I am doing this right and (\alpha) is 45 and (\beta) is -30 ??