What is the difference between an azimuth and a back azimuth?

The distinction between an azimuth and a back azimuth is crucial in navigation and map reading. An azimuth is a directional measurement in degrees from a reference direction, typically true north. It indicates the angle between a target and the observer's position in a clockwise manner.

A back azimuth, on the other hand, is the reverse of the original azimuth. It indicates the direction from the target back to the observer. This reversal is achieved by adding 180 degrees to the azimuth — if the azimuth is less than 180 degrees, or subtracting 180 degrees if it is greater than 180 degrees.

Since the back azimuth is obtained by this method of reversing the original direction, they will always be 180 degrees apart. This relationship is why the choice indicating that they are 180 degrees apart is correct. Understanding this concept is essential for navigation and ensures proper course plotting and orientation in search and rescue operations.