9.1.15 Double integrals

Problem: Find the double integral over the given area: \[ I=\iint_{D} e^{-x^{2}-y^{2}} d x d y, \quad D:\left\{\begin{array}{l} x=\sqrt{1-y^{2}} \\ x=y \\ x=-y \sqrt{3} \end{array}\right. \]