Question

Find the exact value by using a sum or difference identity. cos 19π/12

Answer 1

god am i wrong today. lets try again

Answer 2

\[\frac{19}{12}=\frac{5}{4}+\frac{1}{3}\]

Answer 3

that is what i want. so you have
\[\cos(\frac{19\pi}{12})=\cos(\frac{5\pi}{4}+\frac{\pi}{3})\]

Answer 4

now use addition angle formula for cosine. are you good from there or do you need it worked out?