Definition:Tangent Function/Real

Definition
Let $x \in \R$ be a real number.

The real function $\tan x$ is defined as:


 * $\tan x = \dfrac {\sin x} {\cos x}$

where:
 * $\sin x$ is the sine of $x$
 * $\cos x$ is the cosine of $x$.

The definition is valid for all $x \in \R$ such that $\cos x \ne 0$.