Classification of Conic Sections by Coefficients of General Equation/Historical Note

Historical Note on Classification of Conic Sections by Coefficients of General Equation

In $\text {1604}$, Johannes Kepler introduced the idea that:

pairs of intersecting straight lines

ellipses

parabolas

hyperbolas

are all in fact instances of the various types of conic section, depending on the relative positions of the foci.

In particular, he considered the parabola as a conic section with one focus at infinity.

Sources

• 1998: David Nelson: The Penguin Dictionary of Mathematics (2nd ed.) ... (previous) ... (next): conic (conic section)
• 2008: David Nelson: The Penguin Dictionary of Mathematics (4th ed.) ... (previous) ... (next): conic (conic section)