cross ratio

American  

noun

Geometry.

1. a ratio relating four points in the real or complex plane.

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Other Word Forms

• cross-ratio
  adjective

Etymology

Origin of cross ratio

First recorded in 1880–85

Example Sentences

It is generated by the lines which cut the faces of a tetrahedron in a constant cross ratio, and therefore by those subtending the same cross ratio at the four vertices.

From Encyclopaedia Britannica, 11th Edition, Volume 11, Slice 6 "Geodesy" to "Geometry" by Various

The cross ratio of a range of four collinear points can now be defined as a number characteristic of that range.

From Encyclopaedia Britannica, 11th Edition, Volume 11, Slice 6 "Geodesy" to "Geometry" by Various