This article presents the results obtained in the implementation of computer tools in the teaching of trigonometry in 11th grade at Liceu in Cabinda. Trigonometry is a branch of mathematics used to calculate the Earth's diameter, river widths, distances to make maps, pyramid measurements, algebraic calculations, among others. In their teaching, students have several difficulties such as: graphical representation of trigonometric functions, solving their equations and inequations, determining the domains of these functions, elaborating the concepts of sine, cosine, tangent, cotangent, secant and cosecant from the right triangle, among others. These difficulties were found by applying questionnaires and interviewing teachers and pre-testing 155 11th grade students. Based on this, a didactic alternative was developed in four stages (planning, elaboration, execution and control) using the GeoGebra Mathematical Assistant to favor the teaching-learning process of this content. The evaluation of this Alternative by experts in Mathematics gave rise to satisfactory results that guarantee its validity. These results are the result of the set of activities carried out by students in GeoGebra where more than 70% obtained positive results in the three courses administered at that school.
