Plotting graphs

Periodic Functions

A periodic function is one that repeats over and over again.  There are three common trigonometric ratios that can give periodic functions – sin, cos and tan.  The simplest graphs on a set of x-y axes are just sin(x), cos(x) and tan(x).  Notice that each cycle repeats over every 2p interval, except for tan which repeats over every p interval.  Sin(x) and cos(x) also have y values always between 1 and –1, whereas tan(x) can be anywhere from  to  (negative infinity to positive infinity). Also note that the angles on the x-axis are in radians, not degrees.

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Now of course, there are much more complicated functions than these.  To be able to draw them, you must know the basic shapes shown here.  From these basic curves you can then draw any of the more complicated curves.