I am having a little trouble with this problem. Any help would be greatly appreciated.

The daily consumption (in gallons) of diesel fuel on a farm is modeled by

(PI=3.14....)

where is the time in days, with corresponding to January 1.

a)What is the period of the model? Is it what you expected? explain

so I know the but then how do I simplify that?

b) What is the average daily fuel consumption? Which term of the model did you use? explain.

c)use a graphing utility to graph the model. Use the graph to approximate the time of the year when consumption exceeds 40 gallons per day.

I am confused on the rest, please help. Thank you.