<<
Octagon -
Decagon >>
A
polygon of
nine sides, having an
internal angle sum of 1260
degrees.
Proper name:
enneagon
For a
regular nonagon with sides of
length x,
Area = x
26.182
If each
corner of the nonagon is connected to the 2 furthest corners with
straight lines to form a nonagram, 37 separate areas are formed: 36
triangles and 1 nonagon.