Some Applications of Trigonometry
The line of sight is the line drawn from the eye of an observer to the point in the object viewed by the observer.
Angle of elevation of a point viewed is the angle formed by the line of sight with the horizontal when the point being viewed is above the horizontal level.
Angle of depression of a point on the object being viewed is the angle formed by the line of sight with the horizontal when the point is below the horizontal level.
Trigonometry is used for finding the heights and distances of various objects, without actually measuring them.
Trigonometry was developed to calculate distances from the Earth to the planets and stars.
Computations in astronomy were done with the help of trigonometric tables.