Question

In plane surveying, the area of a tract of land is taken as its projection up on a horizontal plane. However, areas of much larger tracts of land such as a country or a continent are taken as the

Answer 1

In plane surveying, the area of a tract of land is taken as its projection upon a horizontal plane. However, of much larger tracts of land such as a country or a continent are taken as the

 

projection of the tract upon the earth's spheroidal surface at mean sea level

For large area projection is done upon the earth's spheroidal surface at MSL