It should be noted that the protractor is divided into the outer circle and the inner circle. When the zero scale line is in the inner circle, the degree of the inner circle should be read. When the outer circle, the degree of the outer circle can be read. The protractor can not only measure the angle, but also draw any angle. Straight lines, parallel lines, straight lines and parallel lines are not mentioned. The ruler can also be completed. Let's talk about how to use the protractor to draw an angle of a specified angle, This is a function that the ruler does not have (except for special angles).