Angle of depression is measured from:

The angle of depression is a key concept in trigonometry used to describe the angle between a horizontal line and an object located below that line. 1. **Reference Line**: Imagine an observer standing at a height (e.g., on top of a lighthouse). The first step is to establish a **horizontal line of sight**, which is a line parallel to the ground at the observer's eye level. 2. **Object Location**: If the observer looks at an object below them (e.g., a boat in the sea), their eyes must tilt down from the horizontal. 3. **Measurement**: The angle formed between the **horizontal line** and the **line of sight** looking down at the object is the **angle of depression**. Contrarily, if the observer looks at something above the horizontal, it is called the angle of elevation. Therefore, the angle of depression is measured from the **horizontal line of sight, downward**.