### The Students’ Mathematical Argumentation in Circle

#### Abstract

Circle is considered difficult material by many students because of the many elements and formulas they must understand. During this time, students are given questions whose solutions are mechanistic, so that students' understanding cannot be seen. Therefore, it is important to give questions that can reflect students' understanding of the circle through the arguments they give. The main purpose of this study is to obtain information on how students make mathematical arguments in a circle. A total of 36 junior high school students’ answer were analyzed

to see the extent of their understanding of circle through the arguments they gave. Students are given two questions related to the circle material they have learned. The results of the analysis show that students answer correctly about the problem given, but they do not have the right argument to explain why it is true. In particular,

students fail to understand the circle elements when applied in a word-problem. In addition, it was also found that calculation ability is the most common error found in student answers.

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