Quadratic Curves ( Conics )

There are the curve which appears when cone is cut in the plane which doesn't contain a vertex with rigth circular cone.
We knows these conics by names found in Apollonius (BC 247?-205?).

Ellipse
Hyperbola
Parabola


Famous Theorems in Plane Geometry

When it was the 19th century, the geometrical nature of Conics was researched as the development of projective geometry.The followings are intimate relations of conics.

Simson
Brianchon
Pascal