d'Alembert's Theorem
If three Circles 
, 
, and 
are taken in pairs, the external similarity points of the three pairslie on a straight line. Similarly, the external similarity point of one pair and the two internal similarity points of theother two pairs lie upon a straight line, forming a similarity axis of the three Circles.
References
Dörrie, H. 100 Great Problems of Elementary Mathematics: Their History and Solutions. New York: Dover, p. 155, 1965.
- Chow Coordinates
- Chow Ring
- Chow Variety
- Christoffel-Darboux Formula
- Christoffel-Darboux Identity
- Christoffel Formula
- Christoffel Number
- Christoffel Symbol of the First Kind
- Christoffel Symbol of the Second Kind
- Chromatic Number
- Chromatic Polynomial
- Chu Identity
- Church's Theorem
- Church's Thesis
- Church-Turing Thesis
- Chu Space
- Chu-Vandermonde Identity
- Chvátal's Art Gallery Theorem
- Chvátal's Theorem
- ci
- Ci
- Cigarettes
- Cin
- Circle
- Circle Caustic