The representation of the Euclidean plane as the Cartesian product \(\mathbb R^2\) allows us to decompose any vector of the plane into two coordinates, its abscissa and its ordinate. This
The vector rotations of the plane (i.e. centred in the origin), are derived analytically (by coordinates) as linear applications of determinant \(1\), which makes it possible to characterise them integrally
The trigonometric circle allows us to define the cosine, sine and tangent of an oriented angle, and to give an interpretation through Thales' and Pythagoras' theorems.
Introduction: trigonometry and functions
Trigonometry is