postulado 63, poligonos concavos ordenados 20
The length of the diagonal less of them diamonds congruent or of them rhomboid consistent in that is divided 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 square and a rhombus of order ( m, r ) m more that r, r greater or equal that two respectively, and through them, mentally is supposed that is built the polygons concave ordered.