Polygons - Part 1

Definition of polygon

An enclosed figure on a plane bounded by three or more straight sides

Formula of the number of diagonals of a polygon having n sides

Triangle

Number of sides = 3

Quadrilateral

Number of sides = 4

Pentagon

Number of sides = 5

Hexagon

Number of sides = 6

Heptagon

Number of sides = 7

Octagon

Number of sides = 8

Nonagon

Number of sides = 9

Definition of diagonal

A straight line joining any two vertices which are not adjacent to each other