As the name implies, it is an instrument used to measure the degree of angle, which can measure angle, inclination, verticality and levelness. In addition, the protractor is also a drawing tool, which can draw angles, vertical lines and parallel lines. It can be used as an internal and external right-angle ruler to open and close. It can also be used as a long and short ruler to read accurately and intuitively, and draw a circular dimension of the specified size. The protractor is usually made of plastic or iron and is often used with a compass.