Stewart's Theorem
Let a Cevian 
be drawn on a Triangle 
, and denote the lengths 
and 
, with 
. Then
This theorem is sometimes also called Apollonius' Theorem.
References
Altshiller-Court, N. ``Stewart's Theorem.'' §6B in College Geometry: A Second Course in Plane Geometry for Colleges and Normal Schools, 2nd ed., rev. enl. New York: Barnes and Noble, pp. 152-153, 1952. Coxeter, H. S. M. and Greitzer, S. L. Geometry Revisited. Washington, DC: Math. Assoc. Amer., p. 6, 1967.
- Gaussian Prime
- Gaussian Quadrature
- Gaussian Sum
- Gauss-Jacobi Mechanical Quadrature
- Gauss-Jordan Elimination
- Gauss-Kummer Series
- Gauss-Kuzmin-Wirsing Constant
- Gauss-Laguerre Quadrature
- Gauss-Manin Connection
- Gauss Map
- Gauss Measure
- Gauss Multiplication Formula
- Gauss Plane
- Gauss-Salamin Formula
- Gauss's Backward Formula
- Gauss's Circle Problem
- Gauss's Class Number Conjecture
- Gauss's Class Number Problem
- Gauss's Constant
- Gauss's Criterion
- Gauss's Double Point Theorem
- Gauss's Equation (Radius Derivatives)
- Gauss's Formula
- Gauss's Formulas
- Gauss's Forward Formula