Question

match the column a whith column ​

Answer 1

Number of diagonals a polygon of number of sides n is given by

2

n(n−3)

So, an Octagon which has 8 sides has

2

8(8−3)

=20 diagonals.

A Decagon which has 10 sides has

2

10(10−3)

=35 diagonals.

A Pentagon which has 5 sides has

2

5(5−3)

=5 diagonals.

A Hexagon which has 6 sides has

2

6(6−3)

=9 diagonals.