5.5. An EDM instrument without a reflecting prism at station K (elevation = 687 m) is used to sight stations L (elevation = 678 m), M (elevation = 566 m), and N (elevation = 877 m), with the heights of the instrument being 1.5 m for each sighting. The results (ignoring all errors) are as follows:
Inst. @ STA. L, EDM slope distance 897.873 m Inst. @STA. M, EDM slope distance = 1,434.876 m Inst. @STA. N, EDM slope distance 2,800.078 m
Compute the respective observed vertical angles.