From Ratios of Right Triangle to Unit Circle: An Introduction to Trigonometry Function Churun L Maknun, Rizky Rosjanuardi, Al Jupri
Universitas Pendidikan Indonesia
Abstract
Knowing the two contexts of trigonometry both trigonometry as ratios of right-angle triangle and trigonometry as a function is important to students. Educational research has shown that students could not distingush between these contexts and understand why trigonometry is a function. Study showed that a unit circle context can be a glue between them. However, the transition from the triangle concept to unit circle concept is not well delivered. In this study we propose a lesson design for trigonometric to filling the gap between right triangle context and circular function context. This study is underpinned by the previous research proposed by Altman & Kidron (2017) that describe how is students cognitive process through constructing knowlegde. We also report on the results of a classroom case study in which the design has been implemented and researched through a phenomenological investigation based on interviews, classroom observations. We discuss the task-related difficulties that students faced in their concept development. The results of the study suggest that the design can link between trigonometry as ratios of right-angle triangle context and unit circle context. Also, we suggest that prior knowledge of students is the main indicator in order to the design runs well. A consideration of technical support in group work devision is also discussed.
Keywords: Trigonometry, High School Students, Didactical Design, Students Difficulty, Learning Trajectory
