Aset square ortriangle (American English) is an object used in engineering andtechnical drawing, with the aim of providing astraightedge at aright angle or other particular planar angle to abaseline.
The simplest form of set square is a triangular piece of transparentplastic (or formerly of polished wood) with the centre removed. More commonly the set square bears the markings of aruler and a half circleprotractor. The outer edges are typicallybevelled. These set squares come in two usual forms, bothright triangles: one with 90-45-45 degree angles, the other with 30-60-90 degree angles. Combining the two forms by placing thehypotenuses together will also yield 15° and 75° angles. They are often purchased in packs withprotractors andcompasses.
Less commonly found is the adjustable set square. Here, the body of the object is cut in half and rejoined with ahinge marked with angles. Adjustment to the marked angle will produce any desired angle up to a maximum of 180°.
In some European countries a common form of set square combines a 90-45-45 triangle, a ruler and a protractor into a single tool made of stiff or slightly flexible transparent plastic.[1][2][3] Being a mandatory tool used by pupils inmiddle school and higher in German-speaking and neighbouring countries, this specific design is named "Geodreieck [de]" (short form of "Geometrie-Dreieck", meaning "geometry triangle") or similar.[3] It was originally developed in 1964 by the German manufacturerDennert & Pape Aristo-Werke [de] (after several refirmations nowGeotec Schul- und Bürowaren GmbH).[4][5][6][3][7] Relatively uncommon in English-speaking countries, this is sometimes called a "protractor triangle", a term, however, also used for other similar designs. The original design has a hypotenuse length of 15.8 cm and features a 2×7 cm symmetry scale inmillimeter anddegree raster.[3] Variants in larger sizes, with fixed or detachable handles, with or without bevelled edges (facets), and with or without ink nodules or embossed labels exist as well. Some variants have extra markings at angles of 7° and 42° (138° and 173°) in addition to the normal 45° and 90° markings to easedimetricaxonometry per ISO 5456-3,[8] others feature angle scales ingons instead of degrees. Several other somewhat similar designs named "TZ-Dreieck" ("TZ triangle") exist for (larger) technical drawings (TZ from German:Technisches Zeichnen). The scale reaches from 10 to 10 cm, or even 11 to 11 cm.
Similar to theGeodreieck, a number of other protractor triangle types exist fornavigation purposes. Various designs are named navigation (protractor) triangle, nautical navigational triangle, nautical set square, Portland (navigational) triangle or Portland protractor triangle, Kent-type triangle, Inoue-type A/B nautical triangle or plotting triangle, course triangle, yachtsmen triangle, and supporting triangle.
However, some widely used navigational protractors, such as theCras protractor, are not triangles.
[…] 1964 […] Das klassische Geodreieck wird entwickelt und als international registrierte und geschützte Marke eingetragen. Inzwischen millionenfach gefertigt und in vielen Ländern zum Standard-Zeichengerät in der Schule und Ausbildung avanciert […]
