Mathematicians have anold joke about angles being very extro-
verted. How so? Because they are always open! The two rays of an angle
extend out in different directions and continue on forever. Who are the
introverts in mathematics? If you connect three or more line segments end-
to-end you will have a very, shy closed-figure, called a polygon.
By definition, polygons are closed geometric figures that have three or
more straightline segments as sides. Polygons cannot contain arcs or curves,
as illustrated in the figures below.
ABCDPolygon- made of all line segments
- each line segment exclusively
meets the end of another
line segment - all line segments make a
closed figure
A BCNOT a Polygon- AB is not a line segment
- C is not an endpoint
- Figure ABC is not a closed figure
(AC and BC extend infinitely)