mean proportionaln.

Brit.

/ˌmiːn prəˈpɔːʃn̩(ə)l/,

/ˌmiːn prəˈpɔːʃən(ə)l/, U.S.

/ˈˌmin prəˈpɔrʃ(ə)nəl/

Forms: see mean n.³ and proportional adj.

Origin: Formed within English, by compounding. Etymons: mean n.³, proportional adj.

Etymology: Originally < mean n.³ + proportional adj.; later reinterpreted as < mean adj.² + proportional n. Compare Hellenistic Greek μέση ἀνάλογον (Euclid), Middle French, French moyenne proportionnelle (1585), post-classical Latin medius proportionalis (1686 in a British source).

Mathematics and Geometry.

A quantity related to two given quantities in such a way that dividing it by the smaller gives the same result as dividing the larger by it; the geometric mean of two quantities. Cf. extreme and mean ratio at extreme adj. 1b.In quot. c1450 possibly in a different sense.

ΚΠ

c1450 Art Nombryng in R. Steele Earliest Arithm. in Eng. (1922) 47 Betwix euery 2 quadrates ther is a meene proporcionalle, That is openede thus; lede the rote of o quadrat into the rote of the oþer quadrat, and þan wolle þe meene shew.

1571 T. Digges in L. Digges's Geom. Pract.: Pantometria viii. sig. X iij ^v The Ooctaedrons side is meane proportionall betweene the diameter and semidiameter of the circumscribing sphere.

1608 R. Norton tr. S. Stevin Disme: Art of Tenths sig. Diij^v Seeke the meane proportionall betweene BM and his 10 part BR.

1796 C. Hutton Math. & Philos. Dict. (new ed.) I. 269 The distance of the centre of gyration, from the point of suspension, is a mean proportional between those of gravity and oscillation.

1852 G. Salmon Treat. Higher Plane Curves iv. 204 Another..curve of the fourth degree is the conchoid of Nicomedes, invented by that geometer for the solution of the problem of finding two mean proportionals.

1948 C. E. Attwood Pract. Five-figure Math. Tables p. iv Mean proportional parts have been provided for five-figure values of cubes or areas of circles.

1972 M. Kline Math. Thought iv. 93 The conjugate diameter to AB, namely DE,..is defined to be the mean proportional between AB and the latus rectum of the hyperbola.

This entry has been updated (OED Third Edition, March 2001; most recently modified version published online March 2022).

单词	mean proportional
释义	mean proportionaln. Brit. /ˌmiːn prəˈpɔːʃn̩(ə)l/, /ˌmiːn prəˈpɔːʃən(ə)l/, U.S. /ˈˌmin prəˈpɔrʃ(ə)nəl/ Forms: see mean n.³ and proportional adj. Origin: Formed within English, by compounding. Etymons: mean n.³, proportional adj. Etymology: Originally < mean n.³ + proportional adj.; later reinterpreted as < mean adj.² + proportional n. Compare Hellenistic Greek μέση ἀνάλογον (Euclid), Middle French, French moyenne proportionnelle (1585), post-classical Latin medius proportionalis (1686 in a British source). Mathematics and Geometry. A quantity related to two given quantities in such a way that dividing it by the smaller gives the same result as dividing the larger by it; the geometric mean of two quantities. Cf. extreme and mean ratio at extreme adj. 1b.In quot. c1450 possibly in a different sense. ΚΠ c1450 Art Nombryng in R. Steele Earliest Arithm. in Eng. (1922) 47 Betwix euery 2 quadrates ther is a meene proporcionalle, That is openede thus; lede the rote of o quadrat into the rote of the oþer quadrat, and þan wolle þe meene shew. 1571 T. Digges in L. Digges's Geom. Pract.: Pantometria viii. sig. X iij ^v The Ooctaedrons side is meane proportionall betweene the diameter and semidiameter of the circumscribing sphere. 1608 R. Norton tr. S. Stevin Disme: Art of Tenths sig. Diij^v Seeke the meane proportionall betweene BM and his 10 part BR. 1796 C. Hutton Math. & Philos. Dict. (new ed.) I. 269 The distance of the centre of gyration, from the point of suspension, is a mean proportional between those of gravity and oscillation. 1852 G. Salmon Treat. Higher Plane Curves iv. 204 Another..curve of the fourth degree is the conchoid of Nicomedes, invented by that geometer for the solution of the problem of finding two mean proportionals. 1948 C. E. Attwood Pract. Five-figure Math. Tables p. iv Mean proportional parts have been provided for five-figure values of cubes or areas of circles. 1972 M. Kline Math. Thought iv. 93 The conjugate diameter to AB, namely DE,..is defined to be the mean proportional between AB and the latus rectum of the hyperbola. This entry has been updated (OED Third Edition, March 2001; most recently modified version published online March 2022). < n.c1450
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