Τ

Tau in a capital letter Etymologicum Magnum (1499).

Tau (uppercase Τ, lowercase τ; Ancient Greek call ταῦ taû /tâu̯/̯, in Modern Greek ταυ taf /taf/) is the nineteenth letter of the Greek alphabet. The letter tau is the origin of the letters T Latin and Т Cyrillic, which today look identical in their uppercase form but different in their lowercase form.

In the Greek numeral system it has a value of 300 (Τʹ).

History

Epigraphic variants

In archaic epigraphic sources the following variants appear:

Use

In the Greek numeral system it has a value of 300 (τʹ).

τ is used as a symbol of:

• The aureum number 1.618 has numerous mathematical properties, besides being present in nature and art, and is represented by the Greek letter Tau (Τ τ), although more often the letter is used Fi (ш,φ) for this purpose.

• Tau is also used in mathematics to name the constant between the length and radius of a circumference, in such a way that it is equal to 2π and is equal to 6,28318530717958647692528 approximately.

• Constant time in first order RL and RC circuits.

• The pair, torque, torca or moment of strength, vector product of force by distance, which is also usually represented with the letter M.

• The tangential component of tensions produced in deformable solids under the application of a force.

• A subatomic particle of the group of leptons, known as tau particle or tauon in physics. It is also used to represent the average life of a radioactive sample.

• In economics, mainly in macroeconomic models, it is usually used to designate taxes collected by the State.
• In pharmacokinetics, it symbolizes the time interval between the doses of multiple-dose models.

• The cross (tau Franciscana) used by the Franciscans.

• The sign "taw" - "tau" in the Bible

• They are called Tau of Goodman and Kruskal and Tau of Kendall to two non-parametric statistical tests used to measure the relationship between quantitative variables.

In the middle of the name of fray León, between the «e» and the «o» is the vertical stroke of the letter tau, whose transversal lines are shorter and thinner.

In the video game Half life, the Tau (laser beam) cannon and its sequel Half Life 2, in the sand cart of the chapter "Highway 17".

Unicode

• Greek and Coptic

• Maths