A. YUSHA’U, M. Difficult topics in junior secondary school mathematics: practical aspect of teaching and learning trigonometry. Scientific Journal of Pure and Applied Sciences, [S. l.], v. 2, n. 4, p. 161-174, 2013. Disponível em: http://sjournals.com/index.php/sjpas/article/view/984. Acesso em: 22 jul. 2024.