Solving any triangle means calculating its main elements: $a$, $b$, $c$, $\hat{A}$, $\hat{B}$ and $\hat{C}$. To do this, it is necessary to provide three information about the triangle, at least one of which is the measurement of a segment linked to it (side, height, median, etc.). The story The first European treatise dedicated entirely to solving triangles, both plane and spherical, was De triangulis omnimodis (“On triangles of all types”), written around 1464 by the German astronomer Regiomontanus and published only in 1533. He organized the solving cases in a very similar way to what we will do here, and the book was the gateway to trigonometry in Renaissance Europe.