三角測量
a method of surveying the area is divided into triangles and the length of one side and its angles with the other two are measured, then the lengths of the other sides can be calculated
測量方法の1つ 領域を三角形に分割し、1辺の長さおよび他の2辺のなす角度を測定することにより、他の2辺の長さが算出できる