The **parable elements** They are the axis, the focus, the directrix, the parameter, the vertex, the focal length, the chord, the focal chord, the straight side, and their points.

Thanks to these elements or parts, lengths and properties of parabolas can be calculated. The main components from which all other elements arise are the axis, the directrix and the focus.

A parabola is a curved line whose points are equidistant from a focus located on the inside of the curve, and a line called the directrix, located on the outside and perpendicular to the parabola. Geometrically it corresponds to a conic section with eccentricity equal to 1.

**The elements that make up a parabola**

Since all the parabolas correspond to a conic section with the same eccentricity, at a geometric level all the parabolas are similar, and the only difference between one and the other is the scale with which one works.

Normally during the study of mathematics, physics and geometry, parabolas are drawn by hand without taking into account some parameters. For this reason most parabolas appear to have a different shape or angle.

The three main elements that make up a parabola are the focus, the axis and the directrix. The axis and directrix are perpendicular lines that intersect while the focus is a point on the axis.

The parabola constitutes a curved line between the focus and the directrix, all the points of the parabola are equidistant from the focus and the directrix.

**1- Focus **

It is a point located on the axis, any point on the parabola is at the same distance from the focus and the directrix.

**2- Axis**

It is the symmetrical axis of the parabola, the point where the axis cuts the parabola is called the vertex.

**3- Directive**

The directrix is a line perpendicular to the axis to be *opposes* to the parable If located at any point on the parabola to draw a line to the focus, its length will be equal to a line drawn to the directrix.

**4- Parameter**

It is a line perpendicular to the directrix and parallel to the axis that forms a vector between the focus and the directrix.

**5- Vertex**

It corresponds to the intersection point where the axis and the parabola intersect. The vertex of a parabola is at the midpoint between the focus and the directrix.

**6- Focal distance**

It is the distance between the focus and the vertex. It is equivalent to the value of the parameter divided by 2.

**7- Rope**

A chord is any straight line that joins 2 points on a parabola.

**8- Focal chord**

It is a chord that joins 2 points of a parabola passing through the focus.

**9- Straight side**

The straight side is a focal chord parallel to the directrix and perpendicular to the axis. Its value is equal to twice the parameter.

**10 points**

When drawing a parabola, 2 quite differentiable spaces are visually formed on both sides of the curve. These 2 sides make up the interior and exterior points of the parabola.

All those located on the internal side of the curve are known as interior points. The exterior points are those located on the outside, between the parabola and the directrix.

**References**

Parable (nd). Retrieved on December 10, 2017, from Mathwords.

Definition and elements of the parable (sf). Retrieved on December 10, 2017, from Sangakoo.

Parable (nd). Retrieved on December 10, 2017, from Vitutor.

Elements of a parabola (sf). Retrieved on December 10, 2017, from Universo Formulas.

Parable (nd). Retrieved on December 10, 2017, from Math is fun.