<![CDATA[Three-dimensional trigonometry requires students to understand relationships among points, lines, planes, distances, and angles in spatial objects, yet conventional two-dimensional explanations often provide insufficient visual support. This study designed and evaluated an Android-based augmented reality learning application using marker-based tracking to present interactive models of a cuboid, cube, triangular prism, and pyramid. The application was developed with Unity 2022 LTS, Vuforia SDK, C#, and Blender. Its functions include marker scanning, three-dimensional object visualization, explanatory content, an interactive quiz, score feedback, usage guidance, and printable flashcard markers. Functional testing used eleven black-box scenarios on two Android devices, while user evaluation involved 20 students who completed a ten-item questionnaire. All functional scenarios produced the expected output, resulting in a 100% success rate. The Vuforia image targets achieved a four-star rating; the effective detection distance was 17–50 cm, with usable viewing angles between 45 and 90 degrees. Student evaluation produced an average score of 95.1%, classified as good according to the study criteria. The findings indicate that marker-based augmented reality can provide stable spatial visualization, straightforward navigation, and an engaging supplementary medium for learning three-dimensional trigonometry. Future development should expand the learning material, increase the question bank, optimize performance on lower-specification devices, and examine markerless tracking.]]>
