Theta Analysis
The complete orbit along the inside, or around a fixed circle
This workbook illustrates the family of curves called trochoids. To get a trochoid, fix a point on a circular disk (like a reflector in a bicycle wheel) and roll it along another circle. This gives a “spirograph”-like effect in some cases, but using global filters, dashboards, and drag-and-drop exploration, we can generate curves. All of the curves shown in this worksheet are computed by combining functions of "theta," which can be thought of as a measure of orbital angle of the rolling circle as it moves. In other words, when theta goes from 0 to 2*pi, the rolling circle makes one complete "orbit" along the inside, or around, the fixed circle.