STUDENTS’ MATHEMATICAL ARGUMENTATION IN TRIGONOMETRY

Churun L Maknun¹*, Rizky Rosjanuardi², Trisno Ikhwanudin^3
1 School of Postgraduate Studies, Universitas Pendidikan Indonesia, INDONESIA churun@student.upi,edu
² (Dr.) Departemen Pendidikan Matematika, Universitas Pendidikan Indonesia, INDONESIA rizky@upi.edu
³ (M.Ed.) School of Postgraduate Studies, Universitas Pendidikan Indonesia, INDONESIA trisno.ikhwanudin@student.upi,edu
*Corresponding author

Abstract

Trigonometry is a material that many students found difficult. Students should not only tend to lead to the correct procedure or answer, but also how to understand every procedure and applied property. Therefore, it is important to figure out students’ mathematical arguments, that is, reasoning that intends to show, explain why a mathematical result is true. The main purpose of this study is to obtain information how students make mathematical arguments in trigonometry. A total of 36 high school students’ answers was analyzed to understand their understanding of the trigonometry material through their arguments given in each answer. The students were given three questions related to the trigonometry material they had learned. The questions posed in this study cover solving trigonometry equality, trigonometry identities and application of trigonometry which was represented specifically in sine and cosine law. From the analysis, it was found that most of the students answered correctly on the given problem, but they lacked appropriate argument to explain why it is true. In particular, students failed to understand the periodic system in the trigonometric functions. In this study, it is also found that the algebraic ability is the most common error found in students’ answers.

Keywords: argumentation in mathematics, high school student, proof, reasoning, trigonometry, trigonometry equality