7
A polygon with n sides has n*(n-3)/2 diagonals. Simple as that. So a 9 sided polygon has 9*6/2 = 27 diagonals.
A six sided hexagon has nine diagonals.
A nine sided nonagon has 27 diagonals
A 9-sided polygon, is named 'Nonagon'. The number of diagonals are '9' From any one node, to the centre of the opposite side. Since there are 9 nodes and 9 lines, then there will be 9 diagonals.
A regular octadecagon (an eighteen sided polygon) would have nine diagonals.
A nine sided plane figure is a nonagon. A nine sided three dimensional figure is a nonahedron.
nine sided figure = nueve figura una cara nonagon = nonágono
nonagon
nuevegon
Nonagon
A nine sided figure.
It is called a nonagon. There currently is no official name for a nine-sided polygon. However, two names have been proposed for such a figure: the first is a Nonagon; the second is an Enneagon.