10.1.48 Integral of a complex variable
condition: Calculate the integral of a complex variable: \[ \int_{|z|=3} \frac{\cos z d z}{(z+1)(z-4)(z-2)} . \]
Calculation of integrals from functions of a complex variable. Sub-integral functions can be either analytic or with singular points. Application of the main residue theorem, as well as the Cauchy formulas for calculating integrals of functions with poles in a simply connected domain.