The conic sections may be defined in several ways :
Section of a circular cone by a plane (hence the name).
Algebraic curve with degree 2 (equation ax² + bxy + cy² + dx + ey + f = 0).
Locus of points and envelopes.
Circles and directrix lines.
Conic sections as locus of points.
Tangents to conic sections. Conic sections as envelopes of lines.
Construct a conic section, given etc...
Specific case of parabola.
Ellipse considered as a stretched circle.
Properties of asymptotes.
Conic section defined by 5 points.
Homography and Co
Pascal theorem ...
Pencils of conic sections
Constructions (conic section defined by ...)