text: A protractor is a measuring instrument, typically made of transparent plastic or glass, 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.
  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. A protractor divided in centiturns is normally called a "percentage protractor".