A polygon is a flat shape consisting of straight lines that are joined to form a closed chain or circuit. Let’s examine the potential candidates to determine whether they are polygons:
- Triangle: Yes, a triangle has three straight sides and is a polygon.
- Rectangle: Yes, a rectangle has four straight sides and is a polygon.
- Circle: No, a circle is not a polygon because it has curved lines and no straight sides, thus failing to meet the definition of a polygon.
- Pentagon: Yes, a pentagon has five straight sides and is a polygon.
In summary, while triangles, rectangles, and pentagons qualify as polygons, a circle does not due to its curved nature. Polygons must only consist of straight line segments, while circles and other curved shapes fall outside this definition.