## trilinear

[trī lin**′**ē ər]

adjective

of, enclosed by, or involving three lines

Origin of trilinear

tri- + linear## trilinear

adjective

Relating to, having, or bounded by three lines.

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- The general equation to the circle in
**trilinear**co-ordinates is readily deduced from the fact that the circle is the only curve which intersects the line infinity in the circular points. - The equation to a parabola in triangular co-ordinates is generally derived by expressing the condition that the line at infinity is a tangent in the equation to the general conic. For example, in
**trilinear**co-ordinates, the equation to the general conic circumscribing the triangle of reference is 113y+mya+naf3=o; for this to be a parabola the line as + b/ + cy = o must be a tangent. - Hence in
**trilinear**co-ordinates, with ABC as fundamental triangle, its equation is Pa+Q/1+R7=o. **Trilinear**and Tangential Co-ordinates.---The Geometrie descriptive, by Gaspard Monge, was written in the year 1794 or 1 795 (7th edition, Paris, 1847), and in it we have stated, in piano with regard to the circle, and in three dimensions with regard to a surface of the second order, the fundamental theorem of reciprocal polars, viz.**Trilinear**co-ordinates (see Geometry: Analytical) were first used by E.

- trilateration
- trilby
- trilemma
- Trilian
- trilinear