What is defined as a flat closed figure bounded by straight segments?

The definition of a flat closed figure bounded by straight segments precisely matches the characteristics of a polygon. A polygon is formed by a finite number of line segments that connect to form a closed shape. These segments, known as sides, meet at points called vertices. Common examples of polygons include triangles, quadrilaterals, pentagons, and hexagons, illustrating that polygons can have various numbers of sides, as long as they adhere to the criteria of being flat and enclosed by straight lines.

In contrast, a curve does not consist of straight segments and does not meet the criteria for being a polygon. A circle, while a closed figure, is defined by its curved perimeter and does not have straight sides, meaning it cannot be classified as a polygon. A triangle, although a specific type of polygon, is not a complete representation of the broader category since a polygon can encompass many shapes with varying numbers of sides. Thus, the answer is correct in that a polygon encompasses all angles and forms of flat closed figures made only with straight segments.