I have done all that i can for this math project, however there is a few questions that confuse me. Can someone please help me, This is 15% of my final exam???

We are given the data for the monthly temperatures for the city of Rock Hill in 2012.
Jan=(43) Fed=(47) Mar=(54) Apr=(63) May=(70) June=(78) July=(81) Aug=(80) Sep=(73) Oct=(63) Nov=(54) Dec=(45)

The parts i don't get are.....
3.) Find a trigonometric model which closely approximates the data. Use x for the month and y for the average temperature. Tip: y=a sin (bx+c)+d

Question

I have done all that i can for this math project, however there is a few questions that confuse me. Can someone please help me, This is 15% of my final exam???
 
We are given the data for the monthly temperatures for the city of Rock Hill in 2012.
 Jan=(43) Fed=(47) Mar=(54) Apr=(63) May=(70) June=(78) July=(81) Aug=(80) Sep=(73) Oct=(63) Nov=(54) Dec=(45)
 
The parts i don't get are.....
 3.) Find a trigonometric model which closely approximates the data. Use x for the month and y for the average temperature. Tip: y=a sin (bx+c)+d