Which measurement is the primary focus in trilateration surveys?

• A. Angles
• B. Lengths
• C. Pseudorange
• D. Time

Answer: (B)

Trilateration surveys determine a position from known distances to fixed reference points. Each measured distance defines a circle (in two dimensions) or a sphere (in three dimensions) around a reference point, and the intersection of these surfaces pinpoints the unknown location. Because the fundamental data used are those distances, the primary measurement is lengths. Angles belong to triangulation rather than trilateration, and terms like pseudorange or time are related to specific systems (such as GNSS) and involve converting timing into distance, but the direct measurements used in trilateration are the lengths between points.