The three "Spheres Of Position " whose radius are the three

A, B, C are three trigonometric points of known coordinates, and d1 d2, d3, are the respective distances measured from the unknown point O; the equations of the three spheres, with their centers at A, B, C and their radii d1 d2, d3, are given by (1) where the rectangular coordinates of the three known points are Developing (1) with the statements they can be written (2) In Figure 1, we show one of the many configurations of the system of trigonometric points involved in the solution of the system (2); in Figure 2 we have a plain (plain of the sheet) passing for the unknown station and normal to its vertical. The three circumferences with radii r1 r2, r3, are respectively the traces on plain of the three spheres of radii d1 d2, d3, and the points A', B', C are the traces of the respectiv