A polygon in which at least one vertex is "pushed in" or "caved in."
A polygon in which all vertices are "pushed outward."
A point at the end of a line segment or a ray.
A straight path that extends infinitely in opposite directions.
A straight path joining two points. The two points are called the endpoints of the segment.
A quadrilateral that has two pairs of parallel sides. Opposite sides of a parallelogram have equal lengths. Opposite angles of a parallelogram have the same measure.
A 2-dimensional figure (shape) that is made up of three or more line segments joined end to end to make one closed path. The line segments of a polygon may not cross, be curved, or be open.
A polygon that has four sides and four angles.
A straight path that extends infinitely from a point called its endpoint.
A quadrilateral whose sides are all the same length.
A quadrilateral that has exactly one pair of parallel sides.
The point where the rays of an angle, the sides of a polygon, or the edges of a polyhedron meet.