rectilinear figure

A rectilinear figure in mathematics is a shape composed of straight line segments. This means all its sides are straight, and all its interior angles are formed by the intersection of these straight lines. The simplest examples of rectilinear figures are basic geometric shapes like triangles (three sides), quadrilaterals (four sides), and pentagons (five sides).1

These figures can be classified further. A convex polygon has no interior angles greater than 180 degrees, meaning if you extend any side, it won't intersect the polygon. Conversely, a concave polygon has at least one interior angle greater than 180 degrees. Polygons can also be equilateral (all sides equal length) or equiangular (all interior angles equal). When a polygon is both equilateral and equiangular, it is called a regular polygon, such as a square or an equilateral triangle. The term "rectilinear" itself means characterized by or moving in a straight line.12