# Chapter 4. The Wrong Way to Draw a Circle

To most, *trigonometry* is a scary word. I’ll be the first to confess that it utterly bewildered me at school. I remember thinking to myself that I would *never* use this crap in the real world. And I was right—for a couple of years at least.

Until sometime in my late twenties, I found myself making Flash games for a living, and more and more I found bits of half-remembered trig proving useful.

In this chapter, we’ll play with unconventional ways of drawing circles, for which we’ll need a little trig. In the same way we wandered away from the useful convenience of the **line** function in the last chapter, we won’t rely on Processing’s **ellipse** function here. Instead, by working out the math ourselves, we’ll be able to tease out a more nonmechanical, imprecise way of drawing this one shape. Many of my own works have been based on this single idea—rotational drawing algorithms—and so I’ll offer one of them as a case study later in the chapter.