POLYGONS

[Audio] Today we discuss About a new topic which is a polygon. What is a polygon? A polygon is a closed figure with three or more sides. For example we can say that triangle, square, rectangle, pentagon, etc...

[Audio] Next we discuss about regular polygons? What is meant by regular polygon? A polygons which has equal sides and equal angles is known as regular polygon. A triangle, square , pentagon, hexagon, heptagon, octagon.. In the above all shapes have equal angles and equal sides in measures..

[Audio] Next we discuss about inner angles of a polygons. See this picture a triangle. We know that the sum of the angles of the triangle is 180 degree. Here suppose one angle is 70 degree and second angle is 55 degree and the third one is also a 55 degree. Adding all the angles we get the sum of the angles of the triangle. Is it clear ok..

[Audio] Now see this picture a quadrilateral it has four sides and four angles. What about the sum of inner angles of a quadrilateral? Can you guess ok. If I draw a one diagonal in this quadrilateral it split in to two triangles. We know that the sum of inner angles of a triangle is 180 degree. Here it has two triangles . So, the sum of inner angles of a quadrilateral is 2 into 180 degree which is 360 degree.

[Audio] Now see this picture. It is a pentagon. It has 5 sides and 5 angles. What about the sum of inner angles of a pentagon? Can you guess it ok. Suppose if I draw a two diagonals to this pentagon. It split up into 3 triangles right. So, here the sum of inner angles of a pentagon is 3 multiplied by 180 degree. Which means the sum of all angles of a pentagon is 540 degree.

[Audio] Now see this picture. It is a hexagon. It has 6 sides and 6 angles. What about the sum of inner angles of a hexagon? Can you guess it ok. Suppose if I draw a three diagonals to this hexagon. It split up into 4 triangles right. So, here the sum of inner angles of a hexagon is 4 multiplied by 180 degree. Which means the sum of all angles of a hexagon is 720 degree.