Some Applications of Trigonometry | Class 10 Mathematics Notes

Angle of Elevation and Angle of Depression

This section clearly defines the angle of elevation and angle of depression with the help of diagrams. The angle of elevation is the angle formed by the line of sight with the horizontal when the observer looks at an object above the horizontal level, such as looking up at the top of a minar. The angle of depression is the angle formed by the line of sight with the horizontal when the observer looks at an object below the horizontal level, such as looking down at a flower pot from a balcony. These angles are measured from the horizontal line, upwards for elevation and downwards for depression. The section emphasizes that these angles are equal when observed from the same horizontal line due to alternate interior angles formed by a transversal cutting parallel lines. Understanding these angles is essential for applying trigonometric ratios to solve problems involving heights and distances.

📊 Diagram: Fig. 9.2; Fig. 9.3

🧪 Activity: Identify and distinguish angles of elevation and depression in various figures.

🔗 Connection: Prepares for applying these angles in trigonometric problem solving.