Cotangent of Complex Number

Theorem
Let $a$ and $b$ be real numbers.

Let $i$ be the imaginary unit.

Then:

Formulation 3
where:
 * $\cot$ denotes the cotangent function (real and complex)
 * $\sin$ denotes the real sine function
 * $\cos$ denotes the real cosine function
 * $\sinh$ denotes the hyperbolic sine function
 * $\cosh$ denotes the hyperbolic cosine function
 * $\coth$ denotes the hyperbolic cotangent function.

Also see

 * Sine of Complex Number
 * Cosine of Complex Number
 * Tangent of Complex Number
 * Secant of Complex Number
 * Cosecant of Complex Number