Cross-ratio

Rarity: Uncommon

A topic a little better known than average, read and translated beyond its own country.

Rarity follows how well known the article is: its views on the French and English Wikipedia over a year, and the number of languages it exists in.

At a glance

Class

Notion

Domain

Science and technology

In collections

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What Wikipedia says

In geometry, the cross-ratio, also called the double ratio and anharmonic ratio, is a number associated with a list of four collinear points, particularly points on a projective line. Given four points A, B, C, D on a line, their cross ratio is defined as

Excerpt from the Wikipedia article “Cross-ratio”, under the CC BY-SA 4.0 license. Read the article on Wikipedia

Image: Krishnavedala, CC0, via Wikimedia Commons.