Amarasinghe, I.S2024-01-232024-01-232023-11-01Indika Shameera Amarasinghe. (2023). On Ptolemy’s Theorem and Related Derivatives. Proceedings of SLIIT International Conference on Advancements in Sciences and Humanities, 1-2 December, Colombo, pages 302-308.2783-8862https://rda.sliit.lk/handle/123456789/3637In this paper an Euclidean Geometric proof is presented for the Ptolemy’s Theorem of cyclic quadrilaterals by using a generalized identity with respect to a cevian of a triangle. Furthermore, a proof for the converse of the Ptolemy’s Theorem is also presented, while adducing some significant applications, new corollaries and lemmas of Ptolemy’s Theorem and its converse.enCyclic quadrilateralsEquilateral trianglesMathe matical logicPerpendicularsSimilar trianglesArticlehttps://doi.org/10.54389/HBZJ1870