Question

an equilateral triangle is also:
a. a regular polygon
b. an irregular polygon
c. a quadrilateral
d. an open shape

Explanation:

• A regular polygon has all sides and angles equal. An equilateral triangle has all three sides equal and all three angles equal (each \(60^{\circ}\)), so it fits the definition of a regular polygon.
• An irregular polygon has sides and/or angles of different measures. Since an equilateral triangle has equal sides and angles, it is not irregular.
• A quadrilateral has four sides. An equilateral triangle has three sides, so it is not a quadrilateral.
• An open shape does not have all its sides connected to form a closed figure. An equilateral triangle is a closed - sided figure (a polygon), so it is not an open shape.

Answer:

A. A regular polygon