Periodic orbits on a 120-isosceles triangle, 60-rhombus, 60-90-120-kite, and 30-right triangle

Benjamin R Baer, Faheem Gilani, Zhigang Han, Ronald Umble

Research output: Contribution to journalArticlepeer-review

Abstract

A periodic orbit on a frictionless billiard table is a piecewise linear path of a billiard ball that begins and ends at the same point with the same angle of incidence. The period of a primitive periodic orbit is the number of times the ball strikes a side of the table as it traverses its trajectory exactly once. In this paper we find and classify the periodic orbits on a billiard table in the shape of a 120-isosceles triangle, a 60-rhombus, a 60-90-120-kite, and a 30-right triangle. In each case, we use the edge tessellation (also known as tiling) of the plane generated by the figure to unfold a periodic orbit into a straight line segment and to derive a formula for its period in terms of the initial angle and initial position.
Original languageEnglish
Pages (from-to)321-331
Number of pages11
JournalPi Mu Epsilon Journal
Volume16
Issue number6
Publication statusPublished - 1 Jul 2022

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