i.1.75 Double integrals
condition: Change the order of integration: \[ \int_{0}^{a} d x \int_{a-x}^{\sqrt{a^{2}-x^{2}}} f(x, y) d y \]
Double and iterated integrals over various areas of integration, conversion from Cartesian to polar coordinates, calculation of the Jacobian, changing the limits of integration, transformation of variables in the integral.