Protractor Protractor A protractor is a measuring instrument, typically made of transparent plastic or glass, for measuring angles. Most protractors measure angles in degrees (°). Radian-scale protractors measure angles in radians. Most protractors are divided into 180 equal parts. Some precision protractors further divide degrees into arcminutes. They are used for a variety of mechanical and engineering-related applications. One common use is in geometry lessons in schools. Some protractors are simple half-discs. 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
Six Degrees: The Science of a Connected Age Six Degrees: The Science of a Connected Age Six Degrees: The Science of a Connected Age (2004 in paperback, and 2003 in hardcover, ) is a popular science book by Duncan J. Watts covering the application of network theory to sociology. The book covers Watts' own work on small-world networks, and continues on to cover scale-free networks, network searching, epidemics and network failures, social decision making, thresholds in networks, and innovation in large organizations and its lack. In addition to covering the theoretical models and empirical case studies, the book also includes several stories about the character of the researchers