i.1.80 Double integrals
condition: Calculate the double integral over the area \( D \) : \[ \iint_{D} \frac{d x d y}{x^{2}+y^{2}+1}, \quad D: y=\sqrt{1-x^{2}}, y=0 \]
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.