Home plate in the game of Baseball is an irregular Pentagon. However, the Little League rulebook's specification
of the shape of home plate (Kreutzer and Kerley 1990), illustrated above, is not physically realizable, since it requires the
existence of a (12, 12, 17) Right Triangle, whereas
See also Baseball, Baseball Cover
References
Bradley, M. J. ``Building Home Plate: Field of Dreams or Reality?'' Math. Mag. 69, 44-45, 1996.
Kreutzer, P. and Kerley, T. Little League's Official How-to-Play Baseball Book. New York: Doubleday, 1990.