CST Level 1 Land Surveyor Certification Practice

What does a zenith angle measure?

1. A horizontal angle from the benchmark

2. A vertical angle from the zenith direction

3. A distance to the horizon

4. An angle relative to the south direction

The correct answer is: A vertical angle from the zenith direction

A zenith angle measures a vertical angle from the zenith direction. This angle is defined as the angle formed between the line of sight to a point in the sky and the vertical direction directly upward, known as the zenith. In practical terms, when surveying, this measurement is crucial for determining the position of celestial bodies or for applications that involve altimetry and other vertical measurements. Understanding the zenith angle is important in fields like land surveying and astronomy because it helps in calculating the altitude of an object and in aligning surveying instruments correctly. The zenith angle complements the concept of the altitude angle, which measures the angle between the object and the horizontal plane. The other options refer to different types of measurements that do not align with the definition of a zenith angle. For instance, measuring a horizontal angle from a benchmark pertains more to horizontal angles in triangulation methods, while measuring distance to the horizon would relate to horizontal distance or range finding, and angles relative to the south direction typically pertain to azimuths, which describe horizontal angles rather than vertical ones.