Radius Vector
The Vector r from the Origin to the current position. It is also called the Position Vector. Thederivative of 
satisfies
where
is the magnitude of the Velocity (i.e., the Speed).- Antimorphic Number
- Antinomy
- Antiparallel
- Antipedal Triangle
- Antipersistent Process
- Antipodal Map
- Antipodal Points
- Antipode
- Antiprism
- Antiquity
- Antisnowflake
- Antisquare Number
- Antisymmetric
- Antisymmetric Matrix
- Antisymmetric Relation
- Antisymmetric Tensor
- Antoine's Horned Sphere
- Antoine's Necklace
- Apeirogon
- Apoapsis
- Apocalypse Number
- Apocalyptic Number
- Apodization
- Apodization Function
- Apollonius Circles