Secant Exponential Formulation

Theorem
Let $z$ be a complex number.

Let $\sec z$ denote the secant function and $i$ denote the imaginary unit: $i^2 = -1$.

Then:


 * $\sec z = \dfrac 2 {e^{i z} + e^{-i z}}$

Also see

 * Sine Exponential Formulation
 * Cosine Exponential Formulation
 * Tangent Exponential Formulation
 * Cotangent Exponential Formulation
 * Cosecant Exponential Formulation


 * Arcsecant Logarithmic Formulation