Line at Infinity
The straight line on which all Points at Infinity lie. The line at infinity is given interms of Trilinear Coordinates by
which follows from the fact that a Real Triangle will have Positive Area, andtherefore that
Instead of the three reflected segments concurring for the Isogonal Conjugate of a point
on theCircumcircle of a Triangle, they become parallel (and can be considered to meet at infinity). As varies aroundthe Circumcircle, 
varies through a line called the line at infinity. Every line is Perpendicular to theline at infinity.See also Point at Infinity- Principal Direction
- Principal Ideal
- Principal Normal Vector
- Principal Quintic Form
- Principal Radius of Curvature
- Principal Value
- Principal Vector
- Principal Vertex
- Principle
- Pringsheim's Theorem
- Printer's Errors
- Prior Distribution
- Prism
- Prismatic Ring
- Prismatoid
- Prismoid
- Prisoner's Dilemma
- Prizes
- Probability
- Probability Axioms
- Probability Density Function
- Probability Distribution Function
- Probability Function
- Probability Inequality
- Probability Integral