How many diagonals does a hexagon have?

A hexagon has 9 diagonals.

Each vertex of a n-sided polygon can be connected to n - 3 others with diagonals.

Thus n(n - 3) possible diagonals. However, when Vertex A is connected to vertex C, vertex C is also connected to vertex A, thus each diagonal is counted twice.

Thus: number_of_diagonals = n(n - 3)/2

= 6(6-3)/2

= 6x3/2

= 9