HYPERBOLA

(Yunanca köken — orijinale bakınız.) In Geometry, one of the conic sections, formed by cutting a cone by a plane which is so inclined to the axis that when produced it cuts also the opposite cone, or the cone which is the continuation of the former on the opposite side of the vertex. The term hyperbola was given to this curve by A poll on i us on account of its property, that tlie square of any ordinate is greater than the rectangle under the corresponding absci and the parameter, or differs from that rectangle in exce . Like the ellipse and parabola, the hyperbola may be defined in various ways, and all its properties investigated without any reference to the cone, but considered entirely as a plane curve. The definitions most usually adopted are the following: — It two points F and/ be given in a plane, and a point D be conceived to move around them in such a manner that the difference between the two distances D F and (1.) ■^^PD/ is always con stant the point D will describe on the plane an hyperbola [s. 592]