Question

Find an equation of a sphere with radius r and center c(h,k,l)

Answer 1

By defenition of the sphere, the equation is

$(x-c_x)^2+(y-c_y)^2+(z-c_z)^2=r^2,$ or

$(x-h)^2+(y-k)^2+(z-l)^2=r^2.$

Answer: $(x-h)^2+(y-k)^2+(z-l)^2=r^2.$