Nurdin, FadliMashadiNatsir, M.2014-03-252014-03-252014-03-25Rangga Dwijunanda Putrahttp://repository.unri.ac.id/xmlui/handle/123456789/5854This article discusses some alternative proofs of Simson theorem, which states the specific form of the three points of intersection lines on the sides of the triangle. In these alternative proofs, the principle of parallel lines, vertical angle and Menelaus theorem are used. At the end, a particular case found on tangent to Simson line is mentionedothercircumcircleMenelaus theoremSimson theoremOther