These comprehensive RBSE Class 10 Maths Notes Chapter 9 Some Applications of Trigonometry will give a brief overview of all the concepts.

## RBSE Class 10 Maths Chapter 9 Notes Some Applications of Trigonometry

Important Points

1. Line of Sight – The line of sight in the line drawn from the eye of an observer to the point in the object viewed by the observer.

2. Angle of Elevation – Whenever any person/observer or investigator looks an object situated above his natural horizontal level with his eye, then the angle which is formed at that time by the line of sight with the horizontal when the point being looked in above the horizontal level, is called the angle of elevation.

When the person flying the kite looks the flying kite P, then the natural level of his eye will be the horizontal axis ‘OX’ and PM will be the vertical distance of the kite from the horizontal axis ‘OX’ and OP will be called the straight distance from eye to the kite.

Thus, the figure of a right angled in angle OMP is formed where ∠PMO = right angle and ∠POM = 0 will be called the angle of elevation. The angles of elevation are measured upwards from the horizontal.

And then using Pythagoras Theorem for right angled triangle it becomes possible to find the distances OP, OM and PM with the help of Trigonometry.

3. Angle of Depression – When a person is himself at a higher level and looks any object situated below the natural horizontal level of the eye, i.e., when the person has to look downwards to see the object, then in that case the angle, which is formed between the natural horizontal level of the eye and the object, is called the angle of depression.

For example – when any observer which situated at O looks point P, then the angle ∠XOP between the line of sight OP and horizontal line OX is called the angle of depression of P with respect to 0.

4. Angle of Elevation of O with respect to P = Angle of depression of P with respect to O. As shown in the figure given the angle of depression and the angle of elevation are equal.

5. The height or length of an object on the distance between two distant objects can be determined with the help of trigonometric ratio.

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