CST Level 1 Land Surveyor Certification Practice

Which is NOT a type of horizontal angle?

1. Interior angle

2. Deflection angle

3. Zenith angle

4. Exterior angle

The correct answer is: Zenith angle

The correct answer is the zenith angle, as it is not classified as a horizontal angle. A zenith angle is measured from the vertical, specifically defined as the angle formed between a point directly overhead (the zenith) and a point on the horizon. It deals with vertical measurements rather than horizontal, which fundamentally distinguishes it from other types of angles used in surveying. In contrast, interior angles, deflection angles, and exterior angles all pertain to horizontal measurements. Interior angles are the angles formed between two line segments that converge at a point inside a polygon, often seen in the context of triangulation. Deflection angles are the angles measured in a horizontal plane that indicate how much a survey line bends from a previous line, which is crucial for determining changes in direction. Exterior angles are formed outside a polygon, at a vertex, and are defined with respect to the extension of one of the sides. Each of these angles is critical for understanding spatial relationships and measurements in surveying.