9.1.3 Double integrals

Problem: Calculate the mass of the plate \( D \) with density \( \rho \) : \[ D:\left\{\begin{array}{l} x^{2}+y^{2}=4 \\ x^{2}+y^{2}=16 \end{array}, \quad \rho=\frac{2}{x^{2}+y^{2}}\right. \]