Directed Angle
The symbol 
denotes the directed angle from 
to 
, which is the signed angle through which mustbe rotated about 
to coincide with . Four points 
lie on a Circle (i.e., are Concyclic) Iff 
. Itis also true that
Three points
, , and 
are Collinear Iff 
or 
. For any four points, , , , and
,
See also Angle, Collinear, Concyclic, Miquel Equation
References
Johnson, R. A. Modern Geometry: An Elementary Treatise on the Geometry of the Triangle and the Circle. Boston, MA: Houghton Mifflin, pp. 11-15, 1929.
- Diocles's Cissoid
- Diophantine Equation
- Diophantine Equation--10th Powers
- Diophantine Equation--5th Powers
- Diophantine Equation--6th Powers
- Diophantine Equation--7th Powers
- Diophantine Equation--8th Powers
- Diophantine Equation--9th Powers
- Diophantine Equation--Cubic
- Diophantine Equation--Linear
- Diophantine Equation nth Powers
- Diophantine Equation--Quadratic
- Diophantine Equation--Quartic
- Diophantine Quadruple
- Diophantine Set
- Diophantus Property
- Diophantus' Riddle
- Dipyramid
- Dirac Delta Function
- Dirac Matrices
- Dirac's Theorem
- Directed Angle
- Directed Graph
- Directional Derivative
- Direction Cosine