1. The problem statement, all variables and given/known data Find the equation of a sphere of radius 9 which is tangent to the plane x-2y+2z=4 and whose center lies on the x axis. b. Determine the point where the sphere is tangent to the plane. 2. Relevant equations 3. The attempt at a solution My TA told me it might be easier to solver for b first, so I think that the the normal vector of the plane is going to be the same as one of the radii vectors of the sphere, but I really don't know what to do from here could someone point me in the right direction please.