An assignment question I have says

Use thedefinitionto find the first three non-zero terms of the Maclaurin series of f(x) = cos pi x

What does the word "definition" refer to above? Does it mean use the definition of a derivative? Because I've seen that term used a lot in relation to definition of the derivative, or is it more likely use the maclaurin definition of cos x to find cos pi x.

In which case, I think the first three non zero terms are

pi - (pi (x^2))/2!) + (pi(x^4))/4!)