Question

Define
Angle of elevation
Angle of depression
and line of sight

Answer 1

1)The angle of elevation of an object as seen by an observer is the angle between the horizontal and the line from the object to the observer's eye (the line of sight).
2)If the object is below the level of the observer, then the angle between the horizontal and the observer's line of sight is called the angle of depression.
3)The line joining the eyes of the observer and the object is called the line of sight. 

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Answer 2

HI

Angle of elevation : the angle of elevation of an object viewed is the angle formed by the line of sight with the horizontal when it is above the horizontal level that is, the case when we raise our head to look at the object.

Angle of depression : the angle of depression of an object viewed is the angle formed by the line of sight with the horizontal when it is below the horizontal level that is, the case when we lower our head to look at the object.

Line of sight : the line of sight is the line drawn from the eye of an observer to the point in the object viewed by the observer.

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