What is the primary purpose of triangulation in surveys?

The primary purpose of triangulation in surveys is to measure angles between defined points. This method involves establishing a network of triangles, where the angles at each vertex are measured. By knowing the angles in a triangle and at least one side length, surveyors can use geometric principles (such as the law of sines or the law of cosines) to determine the other side lengths and overall distances between points.

Triangulation is particularly effective because it allows for the indirect measurement of longer distances by breaking them down into manageable segments, enabling accuracy even over vast areas. It forms the foundation for many surveying techniques, providing a reliable means to create maps and establish property boundaries.

In contrast, the other options do not represent the primary function of triangulation. Measuring horizontal distances relates more to leveling or other distance measurement techniques, capturing aerial photographs pertains to photogrammetry and remote sensing, and computing area in small regions involves methods such as integration or using planimeter tools rather than the angle-based approach of triangulation.