Circle-Point Midpoint Theorem
Taking the locus of Midpoints from a fixed point to a circleof radius 
results in a circle ofradius 
. This follows trivially from
References
Johnson, R. A. Modern Geometry: An Elementary Treatise on the Geometry of the Triangle and the Circle. Boston, MA: Houghton Mifflin, p. 17, 1929.
- Radial Point
- Radian
- Radiant Point
- Radical
- Radical Axis
- Radical Center
- Radical Integer
- Radical Line
- Radicand
- Radius
- Radius (Graph)
- Radius of Convergence
- Radius of Curvature
- Radius of Gyration
- Radius of Torsion
- Radius Vector
- Radix
- Radon-Nikodym Theorem
- Radon Transform
- Radon Transform--Cylinder
- Radon Transform--Delta Function
- Radon Transform--Gaussian
- Radon Transform--Square
- Rado's Sigma Function
- Railroad Track Problem