9.8.7 Surface integrals

3) Problem: Calculate the surface integral of the \( 1^{\text {st }} \) kind: \[ \mathrm{I}=\iint_{S}\left(x^{2}+y^{2}\right) d s \] where \( S \) is the part of the conical surface \( z=\sqrt{x^{2}+y^{2}} \), distinguished by the condition \( z \leq 1 \).