How is latitude (Lat) computed in surveying?

In surveying, latitude is computed by determining the north-south position relative to the Earth's equator, and this is often derived from measuring angles and distances in a specific way. The correct method involves multiplying the distance of a line by the cosine of its azimuth or bearing.

The cosine function is used because it relates to the horizontal distance that extends northward (i.e., the latitude component) from a point of origin. When you have a distance along a survey line, taking the cosine of the azimuth helps yield the effective north-south component of that line. Essentially, this approach isolates the vertical component of the traveled distance, translating it into an accurate latitude measurement.

This method is fundamental to converting straight-line distances into useful geographic coordinates, critical for mapping and navigation purposes. It provides a mathematically sound means to represent a point's position in terms of latitude, and is integral to the calculations routinely performed in surveying practice.