Abstract
The purpose of this study was to investigate the high school students’ “problem solving performance” when getting involved in the inquiry approach trigonometry teaching. Qualitative case study method was adopted as the research design and the data collection included videotaped and audio-taped classroom teaching practice, group interviews, teacher’s journals and students’ worksheets. The participants were forty-three 11th grade students of a national high school in the middle of Taiwan. Twenty-four hours extra-courses were implemented in six weekends. The research results indicated that there appeared five problem solving approaches: (1) via argumentation; (2) using integrated knowledge; (3) using trigonometric formula; (4) using Pythagorean Theorem; (5) intuition.