Electric field strength

To an observer very close to a spherical surface charge distribution, the sphere's surface looks flat and stretches essentially to the horizon in all directions.  It will therefore look to the observer as if it were an infinite flat charged sheet.  Argue that if the observers distance d from the spherical surface is very small compared to the sphere's radius R, the electric field strength for a uniformly distributed spherical surface charge is the same as that for an infinite sheet