
 The Parabola 
  In the parabola shown in figure 28, point V, which lies halfway between the focus and the directrix, is called the vertex of the parabola. 
  In this figure and in many of the parabolas discussed in the first portion of this section, the vertex of the parabola falls at the origin; however, the vertex of the parabola, like the center of the circle, can fall at any point in the plane. 
  The focal chord is one of the properties of a parabola used in the analysis of a parabola or in the sketching of a parabola. 
 www.tpub.com /math2/13.htm (712 words) 
