How do you use a sum or difference identity to determine the exact values of each trigonometric expression #cos((-5pi)/12)#?
1 Answer
Apr 25, 2015
Use the identity: cos (a - b) = cos acos b + sin asin b
cos (-5Pi/12) = cos (Pi/12 - Pi/2) = cos Pi/12(0) + 0.26(1) = 0.26
cos (-5Pi/12) = 0.26.
