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Mathematics · Ch 5 — Two Dimensional Analytical Geometry-II

Conics

5.3

Conics

Definition 5.2. A conic is the locus of a point that moves in a plane so that its distance from a fixed point (the focus) bears a constant ratio (the eccentricity, ee) to its perpendicular distance from a fixed line not through the focus (the directrix).

This single definition, varying only the value of ee, generates every non-circular conic:

EccentricityConic
e=1e=1Parabola
0<e<10<e<1Ellipse
e>1e>1Hyperbola