KAUFMAN, . Area and perimeter relationship for different shapes with an inradius. Ohio Journal of School Mathematics, [S. l.], v. 92, n. 1, p. 27–31, 2022. Disponível em: http://voyager.janeway.systems:9999/index.php/OJSM/article/view/9155. Acesso em: 7 nov. 2026.