一点对准。把量角器放在角的上面,使量角器的中心对准角的顶点,如图一量角器的中心对准∠ABC的顶点B。二边重合。用量角器的0刻度线与角的一条边重合,如图二量角器的0刻度线与∠ABC的AB边重合。三看度数。角的另一条边所对的量角器上的刻度就是这个角的度数,如上图二,∠ABC另一条边BC所对的量角器上的刻度是120, A little bit aligned. Place the protractor on top of the corner so that the center of the protractor aligns with the vertex of the corner, as shown in Figure 1. The center of the protractor aligns with the vertex B of the ∠ABC. The two sides coincide. The 0 scale of the protractor coincides with one edge of the corner, as shown by the 0 scale of the protractor of Figure 2 coincident with the AB edge of ∠ABC. Three to see the degree. The other side of the corner of the protractor on the scale is the angle of this degree, as shown in Figure 2, ∠ ABC BC on the other side of the protractor on the scale is 120,