Question

The number of diagonals in a hexagon is

• A. 10
• B. 9
• C. 8
• D. 7

Answer 1

The correct option is B 9

Number of diagonals in any $n$ sided polygon is $=$ Total Number of Lines connected two points $-$Total number of sides of polygon

So we have $n$ points so total number of lines is ${=}^n{C}_2$ because we have to choose two points from $n$ points.

Total number of sides $=n$

So, Number of diagonals $=\frac{n(n-1)}{2}-n$

Number of diagonals $=\frac{n(n-3)}{2}$

So number of diagonals in hexagon $n=6$

So, diagonals $=\frac{6(6-3)}{2}=9$