Demonstrações trigonométricas via geometria plana

Abstract

This work has been presented with some trigonometric connections statements only using plane geometry. This proceeding has been realized because we observed that a didactic book only presents algebraic statements. We wish in this way, presents to mathematics teachers and students in high or upper school, trigonometry statements identity using geometry. For this, It has been considered trigonometry cycle only in the first quadrant, given an angle such that α have any α ˂ 90°, extending the reasoning to the other quadrants.