If a Real curve has no singularities except nodes and Cusps, Bitangents, and
Inflection Points, then

where is the order, is the number of conjugate tangents, is the number of Real inflections, is the class, is the number of Real conjugate points, and is the number of Real Cusps. This is also called Klein's Theorem.

**References**

Coolidge, J. L. *A Treatise on Algebraic Plane Curves.* New York: Dover, p. 114, 1959.

© 1996-9

1999-05-26