In mathematics, a parabola is a plane curve that is mirror image symmetric and is still a parabola when the orientation is roughly U-shaped (if different directions are taken). It applies to any one of several ostensibly different mathematical descriptions, all of which can be proven to be exactly the same curve.
One description of a parabola involves a point (focus) and a line (directrix). The focus is not on the straight line. A parabola is the locus of points equidistant from directrix and focus in that plane. Another description of a parabola is as a conical section, formed by the intersection of the conical surface and the plane parallel to the conical bus. The third description is algebra.
Lines that are perpendicular to the directrix and pass through the focus (i.e. break up the parabola through the middle) are called "axes of symmetry". The points on the parabola that intersect the axis of symmetry are called "vertices" and are the sharpest curved points of the parabola. The distance between the vertex and the focus measured along the axis of symmetry is the "focal length". The "line" is the parallel line of the parabola and passes through the focal point. The parabola can open up, down, left, right or in any other direction. Any parabola can be repositioned and repositioned to fit any other parabola - that is, all parabola are geometrically similar.
Parabola have the property that, if they are made of material that reflects light, light traveling parallel to the parabolas axis of symmetry and striking its concave surface is reflected to its focus, regardless of where the parabola is reflected. Instead, light generated from a point source at the focal point is reflected into a parallel (" collimated ") beam so that the parabola is parallel to the axis of symmetry. Sound and other forms of energy have the same effect. This reflective property is the basis for many practical applications of the parabola.
Parabola has many important applications, from parabolic antennas or parabolic microphones to car headlight reflectors to designing ballistic missiles. They are often used in physics, engineering and many other fields.