# Table of Contents

Definition of an equilateral triangle

The criterion for a regular triangle

The area of an equilateral triangle. Formulas

The perimeter of an equilateral triangle

The angle bisector of a regular triangle. Properties

The height of a regular triangle. Properties

The median of a regular triangle. Properties

The property of the angles of an equilateral triangle

The exterior angle bisectors of an equilateral triangle

Similarity of regular triangle

The circle inscribed into an equilateral triangle. Properties

The circle circumscribed around a regular triangle. The theorems

Symmetry in an equilateral triangle