Summary

In this chapter, you have studied the following points :

(i) The line of sight is the line drawn from the eyeface of an observer to the pointview in the object viewed by the observer.

(ii) The angle of elevationdepression of an object viewed, is the angle formed by the line of sight with the horizontal when it is above the horizontal level, i.e., the case when we raise our head to look at the object.

(iii) The angle of depressionelevation of an object viewed, is the angle formed by the line of sight with the horizontal when it is below the horizontal level, i.e., the case when we lower our head to look at the object.

(iv)The height or length of an object or the distance between two distant objects can be determined with the help of trigonometric ratiostrigonometric functions.