Kemampuan Penalaran Matematis Siswa SMA Dalam Menyelesaikan Masalah Tiga Dimensi

The purpose of this study was to describe students' high initial ability, moderate initial ability, and low initial ability mathematical reasoning abilities. The reality in the field shows that students' mathematical reasoning skills in 3D materials are still low and still need to be improved. The subjects in this study were class XII students of SMKF Pekanbaru City totaling 32 students, Riau Province. The research method uses a qualitative descriptive approach. Data collection techniques using written tests, documentation, and interviews. Data analysis using qualitative descriptive analysis by preparing and organizing various kinds of student error data based on each indicator of mathematical reasoning. The results of the research on students' mathematical reasoning ability on each indicator in order are; (1) Presents mathematical statements in pictures 83.3%; (2) Provide reasons or evidence for one or more solutions 55.6%; (3) Make a guess 61.1%; (4) Draw conclusions from statements 63.9%; (5) Checks the validity of an argument 73.6%; and (6) drawing conclusions from several statements 56.5%. The results of this study indicate that mathematical reasoning ability in 3D material in this study 4 indicators are still classified as low. while 2 of them are classified as high.Tujuan penelitian ini untuk mendeskripsikan kemampuan penalaran matematis siswa. Subjek dalam penelitian ini yaitu siswa kelas XII SMKF Kota Pekanbaru, Provinsi Riau. Metode penelitian menggunakan pendekatan deskriptif kualitatif. Teknik pengumpulan data menggunakan tes tertulis, dokumentasi dan wawancara. Analisis data meggunakan analisis deskriptif kualitatif dengan cara menyiapkan dan mengorganisir  macam-macam data kesalahan siswa berdasarkan tiap indikator penalaran matematis sebagai bahan analisis. Dalam analisis ini, kemampuan penalaran matematis siswa diukur berdasarkan masing-masing indikator penalaran matematis. Hasil penelitian tentang kemampuan penalaran matematis siswa pada masing-masing indikatornya secara terurut; (1) menyajikan pernyataan matematika secara gambar 83,3%; (2) memberikan alasan atau bukti terhadap satu atau beberapa solusi 55,6%; (3) mengajukan dugaan 61,1%; (4) menarik kesimpulan dari pernyataan 63,9%; (5) memeriksa kesahihan suatu argumen 73,6%; dan (6) menarik kesimpulan dari beberapa pernyataan 56,5%. Hasil penelitian ini menunjukkan terdapat perbedaan kemampuan penalaran matematis antara siswa berkemampuan awal tinggi, berkemampuan awal sedang, dan berkemampuan awal rendah