Four Coins Problem
Given three coins of possibly different sizes which are arranged so that each is tangent to the other two, find thecoin which is tangent to the other three coins. The solution is the inner Soddy Circle.
See also Apollonius Circles, Apollonius' Problem, Arbelos, Bend (Curvature), Circumcircle,Coin, Descartes Circle Theorem, Hart's Theorem, Pappus Chain, Soddy Circles, SpherePacking, Steiner Chain
References
Oldknow, A. ``The Euler-Gergonne-Soddy Triangle of a Triangle.'' Amer. Math. Monthly 103, 319-329, 1996.
- Sphere Embedding
- Sphere Eversion
- Sphere Geodesic
- Sphere Packing
- Sphere Point Picking
- Sphere-Sphere Intersection
- Sphere with Tunnel
- Spherical Bessel Differential Equation
- Spherical Bessel Function
- Spherical Bessel Function of the First Kind
- Spherical Bessel Function of the Second Kind
- Spherical Bessel Function of the Third Kind
- Spherical Cap
- Spherical Coordinates
- Spherical Design
- Spherical Excess
- Spherical Frustum
- Spherical Geometry
- Spherical Hankel Function of the First Kind
- Spherical Hankel Function of the Second Kind
- Spherical Harmonic
- Spherical Harmonic Addition Theorem
- Spherical Harmonic Closure Relations
- Spherical Harmonic Tensor
- Spherical Helix