Umam, A. K., and A. Isro’il. “BEBERAPA RUMUS TRIGONOMETRI MENGGUNAKAN PENDEKATAN GEOMETRI”. Prosiding Seminar Nasional Matematika Dan Sains, Vol. 5, no. 1, Feb. 2024, pp. 166-71, https://prosiding.biounwir.ac.id/article/view/253.