Delta (letter)
Delta uc lc.svg
Greek alphabet
Αα Alpha Νν Nu
Ββ Beta Ξξ Xi
Γγ Gamma Οο Omicron
Δδ Delta Ππ Pi
Εε Epsilon Ρρ Rho
Ζζ Zeta Σσς Sigma
Ηη Eta Ττ Tau
Θθ Theta Υυ Upsilon
Ιι Iota Φφ Phi
Κκ Kappa Χχ Chi
Λλ Lambda Ψψ Psi
Μμ Mu Ωω Omega
History
Archaic local variants
Digamma · Heta · San · Koppa · Sampi  · Tsan
Ligatures (ϛ, ȣ, ϗ) · Diacritics
Numerals: Greek letter Stigma.svg (6) · Greek Koppa lamedh-shaped.svg (90) · Sampi.svg (900)
In other languages
Bactrian  · Coptic  · Albanian
Scientific symbols

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Delta (uppercase Δ, lowercase δ; δέλτα; Modern Greek [ˈðelta] dhélta) is the fourth letter of the Greek alphabet. In the system of Greek numerals it has a value of 4. It was derived from the Phoenician letter Dalet. Letters that come from delta include Latin D and Cyrillic Д.

A river delta (originally, the Nile River delta) is so named because its shape approximates the upper-case letter delta (the shape is a triangle).

The alphabet on a black figure vessel, with a D-shaped delta.

Contents

Pronunciation

In Ancient Greek, it represented a voiced dental plosive /d/. In Modern Greek, it represents a voiced dental fricative /ð/, like the "th" in "that" or "this". It is romanized as d or dh.

Mathematics and the Sciences

Upper case

The upper-case letter Δ can be used to denote

  • Change of any variable quantity, in mathematics and the sciences; for example, in
{y_2-y_1\over x_2-x_1} = {\Delta y \over \Delta x}, the average change of y per unit x, i.e. the change of y over the change of x
\Delta f = \sum_{i=1}^n {\frac{\partial^2 f}{\partial x_i^2}}
\Delta = b^2 - 4ac\,\!
  • A macroscopic change in the value of a variable in mathematics or science
  • Uncertainty in a physical variable as seen in for instance the uncertainty principle
  • An interval of possible values for a given quantity for instance across a sample[citation needed]
  • Any of the delta particles in particle physics
  • The determinant of the matrix of coefficients of a set of linear equations (see Cramer's Rule)
  • That an associated locant number represents the location of a covalent bond in an organic compound, the position of which is variant between isomeric forms
  • In chemistry, it is often used to represent the addition of heat in a reaction.
  • In legal shorthand, it represents a defendant
  • In the financial markets, it is one of the Greeks that describes the rate of change of an option price for a given change in the underlying benchmark
  • It is the symbol of the Greek inventor and architect Daedalus
  • In genetics, it can stand for a gene deletion, e.g. the CCR5-Δ32 a deletion of the CCR5 at the 32nd base pair segment
  • The American Dental Association cites it (together with omicron for "odont") as the symbol of dentistry.[2]

Lower case

The lower-case letter δ can be used to denote

Meteorology

See also

References

  1. ^ http://ocw.mit.edu/high-school/courses/highlights-of-calculus/big-picture-of-calculus/
  2. ^ ADA.org: Oral Health Topics: Emblem/Insignia of Dentistry[dead link]
  3. ^ "Konglig Datasektionen, Statutes, §2.2 Symbol". D.kth.se. http://www.d.kth.se/sektionen/formalia/stadgar/#paragraf2.2. Retrieved 2010-09-07. 
  4. ^ [1][dead link]

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