The trigonometric functions have features that are worthy of note. Among these features are the period and the amplitude. The graph of f(x)=cos x repeats itself along the x-axis by a certain distance. This distance is called the period. For the cosine function, the period is 2pi radians. It can also be observed that the graph goes up and down by a certain distance. This distance is called the amplitude. For the curve of f(x)=cos x, the amplitude is 1. The main difference between a cosine function and a sine function is that the former is symmetric with respect to the y-axis while the latter is symmetric with respect to the origin.
