Ethnomathematics in the Architecture of the Great Mosque of Medan: Geometric Concepts and Transformations

The Great Mosque of Medan embodies cultural and architectural elements that reflect various mathematical concepts. This study explored ethnomathematical concepts embedded in its architecture and examined their potential as contextual resources for mathematics learning. A descriptive qualitative design with an exploratory orientation was employed. Data were collected through observations, interviews, and documentation involving three purposively selected administrators of the Mosque Management Board (Badan Kenaziran Masjid, BKM). Data credibility was ensured through source and method triangulation and member checking. The data were analyzed through reduction, display, and conclusion drawing to identify mathematical concepts and interpret their relationships with architectural elements and the local cultural context. The findings revealed various geometric concepts, including plane figures such as squares, rectangles, rhombuses, circles, and octagons; solid figures such as cylinders, rectangular prisms, octagonal prisms, square pyramids, and hemispheres; and geometric transformations involving translation, reflection, and rotation. Translation was identified in ornamental patterns associated with elevators and escalators, whereas reflection was evident in staircase arrangements. These findings demonstrate that mathematical concepts are embedded in the mosque's architectural features and can be interpreted within their cultural context. The architecture of the Great Mosque of Medan therefore offers a contextual resource for connecting geometric concepts with local culture and supporting meaningful mathematics learning.