postulado 66, poligonos concavos ordenados 18
The length of the diagonal less of them diamonds congruent or of them rhomboid consistent of a polygon concave ordered of dato ( m, r, n ) m greater that r, r greater that n, n greater or equal that one, is equal to the length of the side lower of those rectangles congruent or of them rhomboid congruent in that is divided a rectangle and a rhomboid of order ( m, r ) m greater than r, r greater than or equal to two respectively, and through this, mentally assumes that the ordered concave polygons were built.