diagonal line

Definition of Diagonal Line

  • The line joining any two non-adjacent vertices of a polygon is called diagonal line.

More about Diagonal Line

  • The number of diagonals of a polygon can be calculated using the formula
    d =, where S is the number of sides in the polygon.
    The number of diagonals in a polygon with 5 sides = = 5.

Example of Diagonal Line

  • In the given figure, A and C, B and D are the non-adjacent vertices.
    The line joining any of these pairs of vertices is called diagonal of the figure.
    So, AC and BD are the diagonals of the given figure.

Solved Example on Diagonal Line

Find the number of diagonals in a regular hexagon.
A. 9
B. 6
C. 12
D. 3
Correct Answer: A
Step 1: A regular hexagon has all of its sides and angles congruent.
Step 2: Draw the diagonals in a regular hexagon.

Step 3: 9 diagonals are formed joining the non-adjacent vertices.
Step 4: So, there are 9 diagonals in a regular hexagon.

Related Terms for Diagonal Line

  • Adjacent
  • Polygon
  • Vertices