Question

an equilateral triangle is a regular polygon. always sometimes never true

Answer 1

Because an equilateral triangle has all sides and internal angles equal. it is ALWAYS a regular polygon

A regular polygon has all sides equal and all internal angles equal. Other triangles are not regular polygons but an equilateral triangle is an exception.

Answer 2

Answer: always true.

The equilateral triangles have all the angles and all the sides congruent.

That is the definition of a regular polygon.