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# Presented by,

Published on: Mar 4, 2016

#### Transcripts - Presented by,

• 1. Name of the teacher : saleena.s Standard:9 unit:1 Topic : interior angles of polygon Objective : To understand that the sum of interior angles a polygon HAVING ‘N’ SIDES =(N-2) *180
• 2. INTERIOR ANGLES OF A POLYGON
• 3. STEPS TO FIND OUT THE INTERIOR ANGLES OF POLYGONS  Polygons can be divided into triangles by joining alternate vertices.  The number of triangles=Two less than the number of sides of the original polygon  Since the sum of angles of a triangle is 180,we can find the sum of angles of polygon by multiplying the number of triangles with 180
• 4. POLYGONS CAN BE DIVIDED INTO TRIANGLES BY JOINING ALTERNATE VERTCES
• 5. SHAPE NUMBER OF SIDES NUMBER OF TRIANGLES SUM OF THE ANGLES (DEGREE) TRIANGLE 3 1=(3-2) 1*180=180 QUADRILATERAL 4 2=(4-2) 2*180=360 PENTAGON 5 3=(5-2) 3*180=540 HEXAGON 6 4=(6-2) 4*180=720
• 6. From the above table we can conclude that the sum of the angles of a polygon having ‘n’ sides is (n-2)180.As the number of sides increases the sum of angles increases by 180 degree