A geometric figure which is formed by 7 straight lines by joining together but the lines should not cross each other, each of two lines meet at a point and form a vertex. So 7 sided polygon has 7 sides and 7 vertices 7 sided polygon is known as heptagon.
Types of polygon: -
· Equilateral polygon is the geometric shapes which consists of all the same sides. For example rhombus is an equilateral polygon because all sides of rhombus are equal.
· Equiangular polygon is the figure when all angles are same. For example rectangle is an equiangular polygon because all angles of rectangle are equal to 90 degrees.
· Regular polygon are those figures whose all sides and angles are equal like equilateral triangle and square are the examples of regular polygon.
Formula of regular polygon
· Sum of interior angle= 180 x (n – 2)
· Each interior angle = 180 x (n – 2) / n
· Sum of exterior angle = 360 degrees
· Each exterior angle =360 / n
· Number of diagonal = n x (n -3) / 2
· Number of triangles = (n – 2)
Where n= length of each side of a regular polygon.
Question: - Find the single exterior angle of a 7 sided polygon.
Each exterior angel =360 / n
= 360 / 7
= 51.43 degrees (approximately).
Question 2: - Find the number of diagonals of 7 sided polygon.
Number of diagonal = n x (n -3) / 2
= 7 x (7 – 3) / 2
There are 14 diagonals in a 7 sided polygon.