# parabolas

## parabola

[puh-rab-uh-luh]
noun Geometry.
a plane curve formed by the intersection of a right circular cone with a plane parallel to a generator of the cone; the set of points in a plane that are equidistant from a fixed line and a fixed point in the same plane or in a parallel plane. Equation: y 2 = 2 px or x 2 = 2 py.

Origin:
1570–80; < Neo-Latin < Greek parabolḗ an application. See parable

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World English Dictionary
 parabola (pəˈræbələ) —n a conic section formed by the intersection of a cone by a plane parallel to its side. Standard equation: y² = 4ax, where 2a is the distance between focus and directrix [C16: via New Latin from Greek parabolē a setting alongside; see parable]

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Etymonline
Word Origin & History

parabola
1570s, from Gk. parabole "parabola, application" (see parable), so called by Apollonius of Perga c.210 B.C.E. because it is produced by "application" of a given area to a given straight line. It had a different sense in Pythagorean geometry. Related: Parabolic.
Online Etymology Dictionary, © 2010 Douglas Harper
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American Heritage
Science Dictionary
 parabola   (pə-rāb'ə-lə)  Pronunciation Key  (click for larger image in new window) The curve formed by the set of points in a plane that are all equally distant from both a given line (called the directrix) and a given point (called the focus) that is not on the line.
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American Heritage
Cultural Dictionary
parabola [(puh-rab-uh-luh)]

A geometrical shape (see geometry) consisting of a single bend and two lines going off to an infinite distance.

Note: An object that is propelled away from the Earth and then drawn back by gravity, such as a fly ball in baseball, follows a path shaped like a parabola.
The American Heritage® New Dictionary of Cultural Literacy, Third Edition