trig fourmulas and proofs

Use the addition formulas to find the exact value of the given expression

1) Cos 11(pi)/12

2) Sin23 cos37 + cos23 sin37

FORMULAS:

sin(u +/- v) = (sin u cos v +\- cos u sin v)

cos(u +/- v) = (cos u cos v -\+ sin u sin v)

tan(u +/- v) = (tan u +\- tan v) / (1 -\+ tan u tan v)

My teacher gave this worksheet and gave the answers and is grading on the work and process... unfortunately i was sick the day we learned how to do these. Any help AND explanation would be greatly apreciated!