PROOF WITHOUT WORDS: TANGENT SUM IDENTITY. Far East Journal of Mathematical Education, [S. l.], v. 27, n. 1, p. 61–62, 2025. DOI: 10.17654/0973563125007. Disponível em: https://pphmjopenaccess.com/fejme/article/view/2963. Acesso em: 5 jan. 2026.