An isonona triangle is one of the following four isosceles triangles: a triangle with two equal angles of , , or . Each can be dissected into similar isonona triangles, all with equal legs. The term isonona is introduced in analogy with the term isohepta [1, p. 218].[more]
This Demonstration shows isonona triangles and their expansions and dissections.[less]
 G. N. Frederickson, Dissections: Plane & Fancy, New York: Cambridge University Press, 1997 p. 218.