Fig. 39.
POLYGON.—A plane figure bounded by straight lines called the sides of the polygon. The least number of sides that can bound a polygon is three. Polygons bounded by a greater number of sides than four are denominated only by the number of sides.
A polygon of five sides is called a Pentagon; of six, a Hexagon; of seven, a Heptagon; of eight, an Octagon; of nine, a Nonagon, etc.
Diagonals of a polygon are lines joining the vertices of angles not adjacent.
The Perimeter of a polygon is its boundary considered as a whole.
The Base of a polygon is the side upon which the polygon is supposed to stand.
The Altitude of a polygon is the perpendicular distance between the base and a side or angle opposite the base.
Fig. 40.