Liouville's Conic Theorem
The lengths of the Tangents from a point 
to a Conic 
are proportionalto the Cube Roots of the Radii of Curvature of at thecorresponding points of contact.
- Dupin's Cyclide
- Dupin's Indicatrix
- Dupin's Theorem
- Duplication Formula
- Duplication of the Cube
- Durand's Rule
- Durfee Polynomial
- Durfee Square
- Dvoretzky's Theorem
- Dyad
- Dyadic
- Dyck's Theorem
- Dye's Theorem
- Dymaxion
- Dynamical System
- Dynkin Diagram
- Dürer's Conchoid
- Dürer's Magic Square
- Dürer's Shell Curve
- e
- Ear
- Early Election Results
- Eban Number
- Eberhart's Conjecture
- Eccentric