Instrument for constructing and measuring plane angles. The simplest protractor is a semicircular disk marked in degrees from 0° to 180°. A more complex protractor, for plotting position on navigation charts, is called a three-arm protractor, or station pointer, and consists of a circular scale connected to three arms. The centre arm is fixed, while the outer two can be rotated to any desired angle relative to the centre one. A related instrument is the course protractor, which allows navigators to measure the angular distance between north and the course plotted on a navigation chart.
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Some protractors are simple half-discs; these have existed since ancient times. More advanced protractors, such as the Bevel Protractor have one or two swinging arms, which can be used to help measure the angle.
External Protractors are instruments used on spheres to find a certain number of degrees. There are all different types of protractors, and they are used to find angles.
Protractors are included as school supplies.
Universal Bevel Protractors are also used by toolmakers, as they measure angles by mechanical contact they are classed as mechanical protractors.
Industrial Protractor provides 0.25[degrees] accuracy.(Introducing "Mite-R-Gage" (protractor) to the Industrial Segment)
Jul 14, 2011; Resistant to breaks, cracks, and warping, Mite-R-Gage consists of two 10 in. arms that rotate 360[degrees] relative to each...