Evaluate ( int_0^ int_0^ e^{-(x^2+y^2 )} dxdy ) by changing into polar coordinates.

Evaluate ( int_0^ int_0^ e^{-(x^2+y^2 )} dxdy ) by changing into

1.	Evaluate ( int_0^ int_0^ e^{-(x^2+y^2 )} dxdy ) by changing into polar coordinates.
A.	( pi )
B.	( frac{ pi}{2} )
C.	( frac{ pi}{4} )
D.	( frac{ pi}{8} )
Answer» D. ( frac{ pi}{8} )