1. The problem statement, all variables and given/known data Find the equation of a sphere of radius 3 which is tangent to both the planes x-2y+2z=3 and 3x+4z=8 2. Relevant equations The only eqn's I need are cross product and MAYBE the distance formula. 3. The attempt at a solution Initially I shifted each normal vector by 3 units and took the cross product, but that just left me with the same answer as if I crossed the initial two normals. I know that you have to do something with a 3 unit shift, but I'm honestly pretty lost. Cheers.