Scolastika Mariani, Abdurrobbil Falaq Dwi Anggoro, Wardono, Bambang Eko Susilo
Lobachevsky geometry is an elective course that is difficult for students to learn. One of them is the concept of the number of angles in a triangle less than 180 degrees. The purpose of this study is to produce a design of a Triangle learning trajectory in Lobachevsky Geometry using the context of the Sumatran traditional snack "lupis cake". The subject of this study is a mathematics education student at one of the universities in Bengkulu province. The research approach used in this study is Design Research. This approach involves an iterative cycle consisting of three phases, namely the preparation phase, the experimental phase, and the retrospective analysis phase. The result of this study is that there are five activities in the learning trajectory of the Triangle in Lobachevsky Geometry using the context of Sumatran traditional snack "lupis cake". Using this context, students are able to find the concept of the number of angles on a triangle less than 180 degrees. The conclusion is that the design of the Triangle learning trajectory in Lobachevsky's Geometry in the context of the traditional Sumatran snack "lupis cake" is valid and practical for finding the number of angles in a triangle. © 2026 by the author(s). Licensed by Lectito Publications, Netherlands. This is an open-access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Universitas Negeri Semarang, Indonesia
