?????? ??????? ?????????? ????, ??????Dutch mathematician Willebrord Snellius (a.k.a. Snel van Royen) launched the modern systematic usage of triangulation. In 1615 he surveyed the gap from Alkmaar to Breda, around 72 miles (116 km). He underestimated this length by 3.five%. The survey was a sequence of quadrangles containing 33 triangles in all.