Final answer:
When an object is below the observer, the acute angle formed by the observer's line of sight and a horizontal line is called the angle of depression, which is relevant in fields like geometry and surveying.
Step-by-step explanation:
If an object being sighted is below the observer, the acute angle formed by the line of sight and the horizontal line is known as the angle of depression. This concept comes into play in various trigonometric applications, often encountered in the context of geometry and surveying.
Definition of Terms:
- Angle of Depression: It is the angle formed by the line of sight and the horizontal line when the object being looked at is below the horizontal level of the observer's eyes. This angle is measured downward from the horizontal.
- Geometry: This is the branch of mathematics that deals with the properties, measurements, and relationships of points, lines, angles, surfaces, and solids.
- Surveying: It is the science or profession of measuring distances, areas, and angles on the Earth's surface for the purpose of establishing maps and boundaries for ownership or governmental purposes.