第2453题：球面方程
求经过四点 (2,0,0)(2,0,0)(2,0,0) ，(0,2,0)(0,2,0)(0,2,0) ，(0,0,2)(0,0,2)(0,0,2) ，(2,2,2)(2,2,2)(2,2,2) 的球面方程。
A. (x−1)2+(y−1)2+(z−1)2=3 (x-1)^2+(y-1)^2+(z-1)^2=3(x−1)2+(y−1)2+(z−1)2=3
B. (x−1)2+(y−1)2+(z−1)2=9 (x-1)^2+(y-1)^2+(z-1)^2=9(x−1)2+(y−1)2+(z−1)2=9
C. (x−12)2+(y−12)2+(z−12)2=34(x-\dfrac{1}{2})^2+(y-\dfrac{1}{2})^2+(z-\dfrac{1}{2})^2=\dfrac{3}{4}(x−21)2+(y−21)2+(z−21)2=43
D. (x−12)2+(y−12)2+(z−12)2=3(x-\dfrac{1}{2})^2+(y-\dfrac{1}{2})^2+(z-\dfrac{1}{2})^2=3(x−21)2+(y−21)2+(z−21)2=3
