The problem ask to calculate and find the value of cos(2npi). So base on the data you have given, we must follow the theories and rule of simplifying and calculating trigonometric expression, so base on that, the answer would be that the cos(2pi) is equals to 1 so the cos(2npi) if even =1 if odd =-1. I hope you are satisfied with my answer and feel free to ask for more
