# cross-ratio

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cross-ratio
cross-raˈtio noun
Of four points in a range, or rays in a pencil, the quotient of the positions ratios of two with respect to the other two
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Main Entry:cross

Useful english dictionary. 2012.

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• cross ratio — cross ratio, adj. Geom. a ratio relating four points in the real or complex plane. Also called anharmonic ratio. [1880 85] * * * ▪ mathematics  in projective geometry, ratio that is of fundamental importance in characterizing projections. In a… …   Universalium

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• cross ratio — noun Etymology: cross (III) : an anharmonic ratio in mathematics * * * cross ratio, adj. Geom. a ratio relating four points in the real or complex plane. Also called anharmonic ratio. [1880 85] …   Useful english dictionary

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