[tex]\text{Cunoa\c stem doar centrul, nu \c si raza.}\\\text{Ecua\c tia sferei de centru B(-1, -3, 3) \c si raz\u a R este: }\\\displaystyle(x-x_B)^2+(y-y_B)^2+(z-z_B)^2=R^2\\\displaystyle(x+1)^2+(y+3)^2+(z-3)^2=R^2.\\\text{Sfera trece prin punctul }A(1,-1,2)\text{ \^inseamn\u a c\u a punctul verific\u a ecua\c tia sferei.}\\(1+1)^2+(-1+3)^2+(2-3)^2=9=3^2\Rightarrow R=3\\\text{Prin urmare, ecua\c tia sferei este: } (x+1)^2+(y+3)^2+(z-3)^2=9[/tex]
