protractorul

Protractorul is a measuring instrument used to determine angles in geometry, drafting, engineering, and construction. It is typically a flat plate marked with degree scales; semicircular models cover 180 degrees, while full-circle versions cover 360 degrees. Many protractorul are transparent to aid alignment with drawings.

The two common forms are semicircular protractorul and full-circle protractorul. Semicircular types include a central pivot and a baseline for aligning one leg of an angle. Bevel protractors and vernier or digital models provide greater flexibility and precision.

Reading a protractorul involves aligning the vertex with the center hole and the baseline with one side of the angle. The other side intersects the scale at the angle measure. Some models feature double scales, allowing readings from either direction.

Materials vary from transparent plastics (acrylic or polycarbonate) to metal such as stainless steel or brass. Transparent variants are favored in drawing for direct line matching and tracing.

Common applications include technical drawing, geometry education, carpentry, metalworking, and surveying. Protractorul enable quick angle transfer, reproduction, and verification, and are often used in conjunction with rulers, compasses, and protractor stands.

Historically, modern protractors emerged with standardized degree systems during the early modern period. Today, they range from simple, inexpensive plastic tools to high-precision digital devices and specialized bevel protractors for machinists.

See also: angle measurement, protractor (geometry), bevel protractor, digital protractor.