Given a reference triangle Δ A B C, the trilinear coordinates of a point P with respect to Δ A B C are an ordered triple of numbers, each of which is proportional to the directed distance from P to one of the side lines. Trilinear coordinates are denoted α:β:γ or (α, β, γ) and also are known as homogeneous coordinates or "trilinears." Trilinear coordinates were introduced by Plücker in 1835. Since it is only the ratio of distances that is significant, the triplet of trilinear coordinates obtained by multiplying a given triplet by any nonzero constant describes the same point, so α:β:γ = μα:μβ:μγ.

areal coordinates | barycentric coordinates | exact trilinear coordinates | major triangle center | orthocentric coordinates | power curve | quadriplanar coordinates | reference triangle | regular triangle center | triangle | triangle center | triangle center function | trilinear line | trilinear polar | trilinear vertex matrix | tripolar coordinates