Question: Consider the following data:

First plot the data, and then try to  determine what nonlinear term(s) are needed. If you elect to use  trigonometric terms, remember to scale the X values so that they all lie  within the interval (0, 2π). Hint: The true model differs slightly from  any of the models given in this chapter, but there are other models,  with polynomial and/or trigonometric terms, that actually fit the data  slightly better than the true model.