Cosine
From specialfunctionswiki
The cosine function, $\cos \colon \mathbb{C} \rightarrow \mathbb{C}$ is defined by the formula $$\cos(z)=\dfrac{e^{iz}+e^{-iz}}{2},$$ where $e^z$ is the exponential function.
Domain coloring of $\cos$.
Properties
Derivative of cosine Taylor series of cosine Weierstrass factorization of cosine Beta in terms of sine and cosine Relationship between cosine and hypergeometric 0F1 Relationship between spherical Bessel y sub nu and cosine Relationship between cosh and cos Relationship between cos and cosh Relationship between cosine, Gudermannian, and sech Relationship between sech, inverse Gudermannian, and cos