Turn (angle)

There are several unit symbols for the turn. EU and Switzerland The German standard DIN 1315 (March 1974) proposed the unit symbol "pla" (from Latin: 'full angle') for turns. Covered in (October 2010), the so-called ('full angle') is not an SI unit. However, it is a legal unit of measurement in the EU and Switzerland. Calculators The scientific calculators HP 39gII and HP Prime support the unit symbol "tr" for turns since 2011 and 2013, respectively. Support for "tr" was also added to newRPL for the HP 50g in 2016, and for the hp 39g+, HP 49g+, HP 39gs, and HP 40gs in 2017. An angular mode TURN was suggested for the WP 43S as well, but the calculator instead implements "MUL" (multiples of) as mode and unit since 2019. == Divisions ==

Many angle units are defined as a division of the turn. For example, the degree is defined such that one turn is 360 degrees. Using metric prefixes, the turn can be divided in 100 centiturns or milliturns, with each milliturn corresponding to an angle of 0.36°, which can also be written as 21′ 36″. A protractor divided in centiturns is normally called a "percentage protractor". While percentage protractors have existed since 1922, the terms centiturns, milliturns and microturns were introduced much later by the British astronomer Fred Hoyle in 1962. Some measurement devices for artillery and satellite watching carry milliturn scales. Binary fractions of a turn are also used. Sailors have traditionally divided a turn into 32 compass points, which implicitly have an angular separation of  turn. The binary degree, also known as the binary radian (or brad), is  turn. The binary degree is used in computing so that an angle can be represented to the maximum possible precision in a single byte. Other measures of angle used in computing may be based on dividing one whole turn into equal parts for other values of . == Unit conversion ==

of the unit circle (whose radius is one) is . One turn is equal to 2\pi = \tau ≈ radians, 360 degrees, or 400 gradians. == In the ISQ/SI ==

In the International System of Quantities (ISQ), rotation (symbol N) is a physical quantity defined as number of revolutions: "Cycle" is also mentioned in ISO 80000-3, in the definition of period. == See also ==