The sine ruler is used to measure angles very accurately. Sinusoidal rulers up to angle 45 can be used, it is no longer useful or it can be said that it is likely to be wrong.
Sinusoidal ruler consists of: support, bases, body and pin. To use the sinusoidal ruler, first we make sure that the ruler is flat, then we use the support to make the piece flat with the size of the measuring block and the distance. Determine the angle value from the center to the center of the sine ruler bases