Polygons, parts and classification

1. Classification of polygons

2. Polygons
The world polygon comes from two Greek
words, poly which means many and gonia
which means angle.
Put together, literally it means many angles. A
polygon is a plane with many angles. It is a
plane bounded by straight line segments

3. Parts of a Polygon
 Side or edge is a line segment that bounds a
plane region.
 Vertex is the point of intersection of two
sides.
 Diagonal is a line segment that connects two
non-adjacent vertices.

4.  Interior angle is the angle inside the polygon
formed by two adjacent sides.
 Exterior angle is the angle outside the
polygon formed by two adjacent sides.
 A regular polygon is one whose sides are of
the same length.

5.  Apothem is the line segment that connects
the center of a regular polygon and the
midpoint of a side.
 Central angle is the angle subtended by a side
about the center of a regular polygon.

7. Characteristics of Polygons
 It is a plane figure, that is, it has two
dimensions.
 It is closed.
 It is bounded by three or more straight line
segments.

9. Regular and Irregular Polygons
Regular polygon is a polygon whose sides have
equal length.All its interior angles are also
congruent. Regular polygons are both
equilateral and equiangular.
If they are not, they are called irregular
polygons.

12. Concave and Convex Polygons
Convex polygon contains no internal angle
larger than 180 degrees.
If it does, it is called a concave polygon.
An angle larger than 180o is also called a reflex
angle.

13. Concave polygonConvex polygon

14. A Simple polygon contains sides that do not
cross over another side.
Complex polygon contains sides that
intersect another side