若∑是球面 ^2+(y)^2+(z)^2-2ax-2ay-2az+2(a)^2=0.-|||-则当 a=1 时, dfrac (1)(pi )(int )_(2)^2(x+y+z)ds= ]-|||-注:∑是球面-|||-((x-a))^2+((y-a))^2+((z-a))^2=(a)^2,