The Thinking Of Muhammad Ibn Muhammad Ibn Al-Hasan Al-Tusi In Trigonometri

This study aimed to determine the contribution of Al-Tusi in geometry and trigonometry. It also aimed to see how he proves the sine rule. In this study there are two issues raised is how the contribution in geometry and trigonometry and how he prove the sine rule. This study used a mathematical approach and historical approach. Mathematical approach used to see trigonometry theories and sine rules. While the historical approach used to see his past. To describe the results documentation method like creation or references relating to him required and data analysis by analytical descriptive done. Based on the results he had a contribution in the proof the fifth postulates of Euclid in Geometry. While in the trigonometry he able to be a pioneer in proving the sine rule and its proof did by the drawing of the circular arc. This is clearly different with general studies studied.