OR
Surveys which are carried out to provide a national grid of control for preparation of accurate maps of large areas, are known
(a) Plane survey
(b) Topographical survey
(c) Geographical survey
(d) Geodetic survey

Ans : – (d) : Geodetic surveying– It is that type of surveying in which the shape of the earth is taken into account. All lines lying in the surface are curved lines and the triangles are spherical triangles.
• It, therefore, involves spherical trigonometry.
• All geodetic surveys include work of larger magnitude and high degree of precision.
• The object of geodetic survey is to determine the precise position on the surface of the earth, of a system of widely distant points which from control stations to which surveys of less precision may be referred.