Plane FiguresClassification of polygons

Parts and Classification of Polygons

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

Parts and Classification of Polygons

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.

Parts and Classification of Polygons

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.

Parts and Classification of Polygons

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.

Parts and Classification of Polygon

Parts and Classification of Polygons

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.

Parts and Classification of Polygon

Parts and Classification of Polygons

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.

Parts and Classification of Polygons

Parts and Classification of Polygons

Parts and Classification of Polygons

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.

Parts and Classification of Polygons

Concave polygonConvex polygon

Parts and Classification of Polygons

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