Isoperimetric Theorem
Of all convex 
-gons of a given Perimeter, the one which maximizes Area is the regular -gon.
- Countably Infinite Set
- Counting Generalized Principle
- Counting Number
- Coupon Collector's Problem
- Covariance
- Covariance Matrix
- Covariant Derivative
- Covariant Tensor
- Covariant Vector
- Cover
- Covering
- Covering Dimension
- Covering System
- Cover Relation
- Coversine
- Coxeter Diagram
- Coxeter-Dynkin Diagram
- Coxeter Graph
- Coxeter Group
- Coxeter Matrix
- Coxeter's Loxodromic Sequence of Tangent Circles
- Coxeter-Todd Lattice
- Cox's Theorem
- Cramer's Rule
- Cramér Conjecture