postulado 84, poligonos concavos ordenados 23
The perimeter of them polygons concave ordered, where the sides of them lines broken have two lengths different and of data ( m, r, n ) m more that r, r greater that n, n greater or equal to one, is equal to 2 ( m r ) by the sum of the lengths of the sides of longer and shorter length of the sides of the broken lines.