A protractor is an instrument used to measure the degree of an angle, which is generally semi-circular. The diameter of the semicircle is the zero scale line of the protractor, and the center of the diameter is the center of the protractor. The scale on the semicircle is the degree used to measure the angle, ranging from 0 to 180 degrees.

Drawing tools are usually made of plastic or iron. You can draw the desired angle according to your needs. Often used with compasses. It can draw angles, measure angles, draw vertical lines, parallel lines, measure inclinations, perpendicularity and levelness. It can be opened and closed as an internal and external right angle ruler. It can also be accurately and intuitively read as a long and short ruler, and draw a circular dimension of the specified size.