A six sided hexagon has nine diagonals.
A nine sided nonagon has 27 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
Nine-sided closed figure
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A six sided hexagon has nine diagonals.
For an n-sided polygon, the number of diagonals is 1+2+3+....+(n-4)+2(n-3). For a nine-sided polygon, there are 1+2+3+4+5+2(6)=27 diagonals.
A nine sided nonagon has 27 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
Nonagon
A nine sided figure.
nuevegon
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.