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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.
Maddox rod test tutorial. Method for measuring vertical deviations: 1. The Maddox Rod is held in front of the patient's right eye with the cylinders vertical, making the red line horizontal. 2. The patient is then asked whether the white light is superimposed on the red line or if it appears above or below the red line.
Similar to the Geodreieck, a number of other protractor triangle types exist for navigation 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 ...
A rolling ruler can draw straight, parallel lines, and also has other instruments included, enabling it to do the jobs of a protractor and compass. [1] [2] The modern rolling ruler, with protractor, pivot pin and multiple pin holes serving as fixed length compasses has been patented in the US in 1991 by Wei Wang. [3]
It can only be used to draw a line segment between two points, or to extend an existing line segment. The compass can have an arbitrarily large radius with no markings on it (unlike certain real-world compasses). Circles and circular arcs can be drawn starting from two given points: the centre and a point on the circle. The compass may or may ...
[6] [7] [8] These tutorial articles remain useful today, but the primary reference for usage is the 1927 Abney Level Handbook. [3] The Abney level is typically used at the eye height of the surveyor, either hand-held or mounted on a staff at that height. To measure lines on a particular slope, the desired angle or grade is first set on the ...
Both apparatus types have an adjustable drawing-head with rules attached to a protractor scale so that the angle of the rules may be adjusted. [6]: 35–36 A drafting machine allows easy drawing of parallel lines over the paper. The adjustable angle between the rulers allows the lines to be drawn in varying accurate angles.
Animation of construction of a pentagon using a compass and straightedge. A mathematical instrument is a tool or device used in the study or practice of mathematics.In geometry, construction of various proofs was done using only a compass and straightedge; arguments in these proofs relied only on idealized properties of these instruments and literal construction was regarded as only an ...