direction calculations
Obtaining a Back Azimuth
To calculate azimuths about a traverse, it is necessary to obtain the back azimuth of a line. To calculate a back azimuth, simply add 180° to the azimuth of the line. In formula form:
For example, if a line has an azimuth of 75º it's back azimuth would be 255º.
Obtaining a Back Bearing
If back bearings are ever needed, all the field engineer needs to do to change the direction is reverse the letters. That is, N 45° E has a back bearing of S 45° W and S 82° 20' E has a back bearing of N82° 20' W.
