What is a Polygon?.
The word polygon is a combination of two Greek words: "poly" means many and "gon" means angle. Along with its angles, a polygon also has sides and vertices. "Tri" means "three," so the simplest polygon is called the triangle, because it has three angles. It also has three sides and three vertices. A triangle is always coplanar, which is not true of many of the other polygons.
Basically, polygons are many-sided figures, with sides that are line segments. They are named according to the number of sides and angles they have. The most common polygons are the triangle, rectangle and the square.
polygon is one that has equal sides, like a square, equilateral triangle etc.
The table lists all the polygons having up to 10 sides. (it is extracted from www.math.com)
Types of Polygon
Regular - all angles are equal and all sides are the same length.
Regular polygons are both equiangular and equilateral.
Special Triangles - right, equilateral, isosceles, scalene, acute, obtuse.
Formulas relating to polygons
Area of a regular polygon = (1/2) N sin(360°/N) S2
Sum of the interior angles of a polygon = (N - 2) x 180°
The number of diagonals in a polygon = 1/2 N(N-3)