CONIC SECTION

curve in which a plane intersects a cone. All the po ible resulting curves obtained thus, are: patr of intersecting straight lines, circle, ellipse, parabola, and hyperbola. Geometrically, the last three curves are defined as: the locus of a point moving so that the ratio of its distance from a fixed point, called the focus, to its distance from a fixed straight line, called the direct riz, is constant. This ratio, called the eccentricity, is le than, equal to, and greater than, unity, for the ellipse, parabola, and hyperbola respectively. The circle is a particular case of the ellipse. Analytically, a conic section is represented by an equation of the second degree of the form az? bbry-+cy?+da+ey+f=9.