Hidden Properties of the Equilateral Triangle

The equilateral triangle provides a rich context for students and teachers to explore and discover geometrical relations using GeoGebra. In this paper, we provide teachers with interactive applets to use in their classrooms to support student conjecturing regarding properties of the equilateral triangle. Proofs of the properties are then presented. Proofs make use of theorems in geometry, trigonometry, coordinate geometry, as well as inequalities about numbers.