In
geometryGeometry arose as the field of knowledge dealing with spatial relationships. Geometry was one of the two fields of pre-modern mathematics, the other being the study of numbers....
, a
protractor is a circular or semicircular tool for measuring an
angleIn geometry and trigonometry, an angle is the figure formed by two rays sharing a common endpoint, called the vertex of the angle...
or a
circleA circle is a simple shape of Euclidean geometry consisting of those points in a plane which are equidistant from a given point called the centre. The common distance of the points of a circle from its center is called its radius....
. The units of measurement utilized are usually
degreeA degree , usually denoted by ° , is a measurement of plane angle, representing 1⁄360 of a full rotation; one degree is equivalent to π/180 radians...
s.
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.
A Bevel Protractor is a graduated circular protractor having a pivoted arm; used for measuring or marking off angles.
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In
geometryGeometry arose as the field of knowledge dealing with spatial relationships. Geometry was one of the two fields of pre-modern mathematics, the other being the study of numbers....
, a
protractor is a circular or semicircular tool for measuring an
angleIn geometry and trigonometry, an angle is the figure formed by two rays sharing a common endpoint, called the vertex of the angle...
or a
circleA circle is a simple shape of Euclidean geometry consisting of those points in a plane which are equidistant from a given point called the centre. The common distance of the points of a circle from its center is called its radius....
. The units of measurement utilized are usually
degreeA degree , usually denoted by ° , is a measurement of plane angle, representing 1⁄360 of a full rotation; one degree is equivalent to π/180 radians...
s.
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.
Bevel Protractor
A Bevel Protractor is a graduated circular protractor having a pivoted arm; used for measuring or marking off angles. Sometimes vernier scales are attached to give more accurate readings. It has wide application in architectural and mechanical drawing although with the availability of modern drawing software or CAD the tool is less commonly used in that sphere.
Universal Bevel Protractors are also used by toolmakers, as they measure angles by mechanical contact they are classed as mechanical protractors.
See also
- Protractor compass
- Goniometer
A goniometer is an instrument that either measures angle or allows an object to be rotated to a precise angular position. The term goniometry is derived from two Greek words, gonia, meaning angle and metron, meaning measure.-Audio:...
- Geometry template
A geometry template is a piece of clear plastic with cut-out shapes for use in mathematics and other subjects in primary school through secondary school. It functions as a stencil, protractor, ruler, and straightedge. It can also be called a mathomat....
- Inclinometer
An inclinometer or clinometer is an instrument for measuring angles of slope , elevation or inclination of an object with respect to gravity...
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