What is Trigonometry? | Introduction to Trigonometry | Don't Memorise

Tacheometry * Tacheometry is a method of surveying in which horizontal distances and differences in elevations are determined by measuring intercepts on a graduated scale and angles by using theodolite. * This method is not tedious and speed of surveying is very high. However, accuracy is less. * If interval between stadia hairs is i, intercept on staff is s, f is focal length and d is the horizontal distance between the objective and the vertical axis of the instrument, then the distance between instrument station and the position where the staff is held is D = s + (f + d) = ks + C where k = and C = f + d k is known as multiplying constant and C is additive constant. Usually, in all instruments-manufacturers keep k = 100 and C varies from 0.3 to 0.6. These values can be determined by carrying out measurements over known distances. Manufacturers write these values on the instrument also. * With simple geometric relations, the elevations and distances can be found with inclined sights a...