👉 In mathematics, "fontanels" is a term used to describe the set of all points on the surface of a sphere that are at a fixed distance from a given point. The distance between two points on the surface of the sphere is called the radius of curvature of the surface. For example, consider a sphere with center O and radius R. Let P be any point on the sphere. Then the set of all points Q on the sphere that are at a fixed distance r from P (

fontanels