PrefaceThis book is intended to serve as a reference for the contents of Trigonometry Course taught at High School.The contents of the discipline Trigonometry supposes that the course of Basic or Plane geometry has already been taught previouslyThe content begins with the basic definitions of magnitudes, vectors and sums of vectors as well as their projections.Next, the oriented circumference is then defined, and arcs and their multiples are also presented.The trigonometric functions are defined with all their characteristics in a chapter exclusively dedicated to functions presentation.Three chapters are dedicated to operations using functions starting with basic forms, methods for reduction to the first quadrant and ending with addition and subtraction of arcs.A chapter is reserved to the construction of a table with the functions values for arcs with remarkable values.The penultimate chapter presents methods used to solve trigonometric equations, presenting solved exercises and exercises to be solved.The last chapter presents methods for solving problems related to right triangles and general triangles.Also in this last chapter is presented a review of topics of plane geometry, necessary to solve problems related to triangles.