Parabola is a curve generated through a point moving hence that at any position its distance from a fixed point or the focus, F is usually exact equal to its distance to a fixed line or the directrix, AB, as displayed in diagram.
For construct a parabola when focus F and the directrix AB are specified, sketch the axis of the parabola perpendicular to the directrix AB. Via any point on axis, as like example point C, sketch a line parallel to the directrix AB. By using F as a center and distance OC like a radius, strike arcs intersecting the line at points P4 and P′4. Repeat this procedure till an enough number of additional points have been located to find out a smooth curve. The vertex V is situated at a point midway among O and F.