👉 "Cosen" is a term in the mathematical field of complex analysis, specifically in the context of the study of the functions of a complex variable. It was introduced by the French mathematician Paul de la Vallée-Poussin and has since become an important tool for studying the behavior of certain complex-valued functions on the complex plane. In complex analysis, "cosen" refers to the complex function given by the formula: \[ \text{cosen}(z) = \frac