Sagitta
The Perpendicular distance 
from an Arc's Midpoint to the Chord across it, equal to theRadius 
minus the Apothem 
,
 | (1) |
, |  |  | |
 |  | (2) | |
|  | (3) | |
|  | (4) |
where
is the Circumradius, the Inradius, is the side length, and 
is the number of sides.See also Apothem, Chord, Sector, Segment- Diagonal Ramsey Number
- Diagonal Slash
- Diagonal (Solidus)
- Diagonals Problem
- Diagram
- Diameter
- Diameter (General)
- Diameter (Graph)
- Diamond
- Dice
- Dichroic Polynomial
- Dido's Problem
- Diesis
- Diffeomorphism
- Difference
- Difference Equation
- Trigonometry Values Pi/4
- Trigonometry Values Pi/5
- Trigonometry Values Pi/6
- Trigonometry Values Pi/7
- Trigonometry Values Pi/8
- Trigonometry Values Pi/9
- Trigyrate Rhombicosidodecahedron
- Trihedron
- Trilinear Coordinates