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A half-circle protractor marked in degrees (180°). A protractor is a measuring instrument, typically made of transparent plastic, for measuring angles. Some protractors are simple half-discs or full circles. More advanced protractors, such as the bevel protractor, have one or two swinging arms, which can be used to help measure the angle.
Invented in 1915 by Temporary Lieutenant (later Captain) Carrol Romer, M.C., R.E. (1883–1951), then "Maps", First Army: i.e. OC Maps and Printing Section, such reference cards were widely used by the British Army in World War I and after, being described in a Maps GHQ booklet Maps and Artillery Boards in December 1916.
Various scales and the protractor are used to measure the lengths of lines and angles, allowing accurate scale drawing to be carried out. The compass is used to draw arcs and circles. A drawing board was used to hold the drawing media in place; later boards included drafting machines that sped the layout of straight lines and angles.
A drafting machine is a tool used in technical drawing, consisting of a pair of scales mounted to form a right angle on an articulated protractor head that allows an angular rotation. [ 1 ] [ 2 ] The protractor head (two scales and protractor mechanism) is able to move freely across the surface of the drawing board , sliding on two guides ...
The length is copied from the point to O'. This will become the centre used by circular protractor. Draw a line from here to crossing of the vertical and the long-line. The circular protractor is aligned so that zero falls on the new line. Points are marked off and lines drawn through them to the long line.
A 360 degrees protractor with graduations in degree: Date: 2 December 2007: Source: Personal work, based on a public domain licensed file, downloaded from Wikipedia (Image:Protractor.svg) Author: Georges Khaznadar <georgesk@ofset.org> Other versions
Amanda explains what Wesley was doing in the caption, "In the scene, the actor is to check a notification on his phone. Each time the actor tried to look at his phone, Wesley thought he was taking ...
The protractor head has a flat reference edge which is attached to an adjustable 180° protractor or (sometimes called a turret) with a graduated scale in both directions for reading both the angle or the complement angle. [1] The protractor head sometimes includes a small spirit level. [4] [2]