Delta

For the place where a river ends, see River delta.

Delta (uppercase/lowercase Δ δ), is a letter of the Greek alphabet, used to represent the "d" sound in Ancient and Modern Greek. In the system of Greek numerals, it has a value of 4. Letters that came from it include the Roman D and Cyrillic Д.

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
Other letters
Ϝϝ	Digamma	Ⱶⱶ	Heta
Ϻϻ	San	Ϙϙ	Koppa
Ϡϡ	Sampi	Ϛϛ	Stigma
Ϸϸ	Sho
Category Commons

In mathematics, the upper-case letter Δ can be used as symbol to represent "change" in a variable (e.g., [math]\displaystyle{ \Delta x }[/math]). It can also be used to represent discriminant—a key algebraic expression used to determine the number of roots a polynomial has. The lower-case letter [math]\displaystyle{ \delta }[/math], on the other hand, is often used to denote small quantities in proofs involving limit, a key concept on calculus is based on.

In molecular chemistry, the lower case Greek letter δ is used to represent a partial charge. This is always less than the unit charge associated with an ion, but has no real fixed value.

A river delta is so named because its shape approximates the upper-case letter delta.

Related pages

• Epsilon