Parabola, << puh RAB uh luh, >> is one of the curves most used in science. If a ballplayer hits a high fly, the path of the ball is nearly a parabola. Any point on a parabola is the same distance from a line AB as it is from point C. Line AB is the directrix and point C is the focus. The solid line through point C, which bisects the parabola, is called the axis.
A parabola revolved about its axis generates a parabolic surface. A light at the focus of a mirror with this shape would cause the light rays that hit the mirror to reflect parallel to the axis. Scientists use this principle of the parabolic surface in producing headlight and searchlight reflectors.
