Digital Text - Std 8 Maths Polygons

                                        DIGITAL  TEXT

Name of the teacher:  Aparna Venugopal

Subject        :    Mathematics

Class    :  8

Unit :  Polygons

Sub unit : Shapes

Learning Objectives 

By learning the topic, learner will be able to :

• Learn the concept of polygons

• Name different polygons

• Identify non – polygons and polygons

• Understand the characteristics of polygons

         

 INTRODUCTION

    Look around.What all shapes do you see in your surroundings? Can you name them?

 We are already familiar with shapes like triangle, square, rectangle,parallelogram etc.. Now take your note book and draw horizontal and vertical dots.Then join 3 dots using straight lines to form a triangle.Now join four dots to make the shape. Which shape did you get? Yes..you have drawn a quadrilateral.

Now try to join 5 dots to get a shape.Which shape is this? Are you familiar with it? Let us look which shape you have got.

                                                       POLYGONS

 

     The closed figure having five sides and five angles made using straight lines is  called Pentagon. In Greek,  the word “ Penta” means five and “agon” means angle. Thus Pentagon means a shape having five sides and angles.

 Click here to see the shape Pentagon.

  Now, similiarly by joining 6 dots, we get a closed figure with six sides.

It is called Hexagon. A closed figure having six sides and six angles and six vertices is called Hexagon. In Greek, the word “Hexa”  means six. Thus hexagon means a shape having six sides and six angles.

Given below is the shape Hexagon :

      

   Similiarly by increasing the number of sides, we get such figures.

   Generally, such figures are collectively called Polygons.

   Thus,

So, triangle, quadrilateral,pentagon, hexagon,….etc  are the different polygons

Of them, Triangle is the smallest polygon.

 Here is the table of different polygons upto 10 sides:

         

For knowing more about Polynomials, see the video by clicking on the video icon below :

  Video

 We have seen that Polynomials are made up of straight lines. So the shapes drawn using curves are not polygons. Here are some examples of non -polygons :

                                        - THANK   YOU -