Resumen de Direcciones de Cavalieri entre dos triángulos
Although Cavalieri principles were set forth in the XVII century, they already appeared implicit in Archimede´s discoveries about areas and volumes. The application to triangles of the first principle admits a reciprocal theorem: any two triangles of the same area are always Cavalieri-congruent. This result was discovered and proved in 1988 and other proofs have appeared since them. In this article the problem is developed following several lines: 1) giving another solution based on a unique rotation; 2) determining the number of directions for the sheaf of parallel lines; 3) calculating such directions depending on the two triangles.
