Trigonometry is the study of relationships between the sides and angles of a triangle. It is used in geography and in navigation. It is also used in constructing maps, determine the position of an Island in relation to the longitudes and latitudes.
In this chapter trigonometry is used for finding the heights and distances of various objects without actually measuring it.
The line joining the observer’s eye and the object observed is known as Line of Sight.
The angle between the horizontal line and the line of sight which is above the observer’s eye is known as Angle of Elevation.
The angle between the horizontal line and the line of sight which is below the observer’s eye is called Angle of Depression.