

Nonagon (9gon) (also Enneagon)
From Latin: nonus  "ninth"
Try this
Adjust the nonagon below by dragging any orange dot. By clicking on the top left command line,
you can switch it between a
regular and
irregular nonagon.
Properties of regular nonagons
Properties of all nonagons
Number of diagonals 
27 
The number of distinct diagonals possible from all vertices. (In general ½n(n–3) ).
In the figure above, click on "show diagonals" to see them.
See Diagonals of a Polygon 
Number of triangles 
7 
The number of triangles created by drawing the diagonals from a given vertex. (In general n–2).
In the figure above, click on "show triangles" to see them. See Triangles of a Polygon 
Sum of interior angles 
1260° 
In general 180(n–2) degrees .
See Interior Angles of a Polygon 
Other polygon topics
General
Types of polygon
Area of various polygon types
Perimeter of various polygon types
Angles associated with polygons
Named polygons
(C) 2011 Copyright Math Open Reference. All rights reserved

