Goniometer
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A goniometer is an instrument that either measures an angle or allows an object to be rotated to a precise angular position. The term goniometry derives from two Greek words, γωνία 'angle' and μέτρον
Goniometer made by Develey le Jeune in Lausanne, late 18th–early 19th century
A half-circle protractor marked in degrees (180°).
A half-circle bevel protractor
A universal bevel protractor.
Set square
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A set square or triangle is an object used in engineering and technical drawing, with the aim of providing a straightedge at a right angle or other particular planar angle to a baseline.
Variant of larger TZ-Dreieck with extra markings
Navigational Cras protractor (foreground)