English: All of the six trigonometric functions of an arbitrary angle θ can be defined geometrically in terms of a unit circle centred at the origin of a Cartesian coordinate plane. The values of ${\displaystyle \sin (\theta )}$, ${\displaystyle \tan (\theta )}$, and ${\displaystyle \csc (\theta )}$ are represented by the ordinates of points A, B, and D, respectively, while the values of ${\displaystyle \cos (\theta )}$, ${\displaystyle \cot (\theta )}$, and ${\displaystyle sec(\theta )}$ are represented by the abscissas of points A, C and E, respectively.