Nearly any function you are likely to encounter in a physics class, to the best of my knowledge, is analytic (IANAP).
Another way to look at this is: “almost all” smooth functions are “nearly” polynomials. Why should trigonometric functions be “nearly” polynomials? Why should exponentials? Why should there be any connection at all between the trig functions and the polynomials? I still say this is a surprising result.