Which tool is primarily used for measuring distances in surveying?

The theodolite is primarily used for measuring angles in surveying, but it also incorporates distance measurement capabilities when paired with other instruments such as electronic distance measurement (EDM) devices. The key aspect of theodolites is their high precision in measuring both horizontal and vertical angles, which, when combined with EDM, allows for very accurate surveying over distances.

While a tape measure is commonly used for shorter measurements and can provide direct distance readings, it lacks the precision and capability needed for larger surveying projects. A rangefinder, on the other hand, is used for measuring distance to a specific object but is not typically employed across the breadth of surveying tasks that require detailed angle measurements. GPS devices are useful for determining locations and conducting large-scale mapping, but they rely on satellite data and can be less accurate in certain environments compared to traditional surveying methods.

In summary, the utilization of a theodolite, especially when combined with electronic distance measuring capabilities, makes it a key tool in surveying for achieving accurate distance and angle measurements.