NGUYEN, N.-G. . Teaching the Law of Cosines in Advanced 10th Grade Geometry Textbook by Way of Problem-Based Learning in Vietnam. International Journal of Learning, Teaching and Educational Research, [S. l.], v. 18, n. 11, p. 397–413, 2019. Disponível em: http://ijlter.net/index.php/ijlter/article/view/465. Acesso em: 8 jun. 2026.