Historical Angular Measurement

Abstract

The quantification and measurement of angles is important in scientific, as well as every day, applications. Several systems have been developed to quantify angles beginning in ancient times. Most systems begin with a circle and divide the circle into equal segments of arc. Measurement of the angles thus defined has been accomplished by using a number of devices and/or the functions defined by trigonometry. There are two common angle systems in use today: English/U.S. standard of degree-minute-seconds and the SI standard of radians. For solid angles, the SI standard is the steradian. From a practical standpoint, the use of degrees is far more common. This chapter reviews the history of the approaches to defining angles and provides methods for converting between angular measurements.