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Subject – Mathematics

Chapter 7 – GEOMETRY

Sub-topic 3 : Different polygons, quadrilaterals and introducing triangle as a

polygon.

 Introduction–A simple closed curve made up of line segments only is called a polygon.

 Regular polygons are polygons that have sides with equal length and interior angles with
equal measure. Irregular polygons are polygons that are not regular, so they do not have
sides with equal length or interior angles with equal measure.
 Irregular polygons can still be pentagons, hexagons and nonagons, but they do not have
congruent angles or equal sides. Here are some examples of irregular polygons. In these
polygons, some sides are clearly longer than others and some angles are wider than others, so
they must be irregular.
 Classification of polygons
 Number of sides  Name of the polygon Shapes
or vertices
 3  Triangle

 4  Quadrilateral( square,
Rectangle,Rhombus,Parallelogram)

 5  Pentagon

 6  Hexagon

 7  Heptagon

 8  Octagon

 9  Nonagon