mean proportional

American  

noun

Mathematics.

1. (between two numbers a andb ) a number x for which a/x = x/b .

   The number 3 is a mean proportional between 1 and 9.

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Etymology

Origin of mean proportional

First recorded in 1565–75

Example Sentences

Then the whole line DC is 141,289; and CP, which is a mean proportional between DC and CN, since MD touches the Ellipse, will be 105,032.

From Treatise on Light by Huygens, Christiaan

Then the whole line CZ is 139,655; and CS, which is a mean proportional between CZ and CO will be 93,410.

From Treatise on Light by Huygens, Christiaan

The perpendicular is the mean proportional between the segments of the hypotenuse.

From The Teaching of Geometry by Smith, David Eugene

Then x - 5 is a mean proportional between x - 9 and x, from which we find that x equals 25.

From Amusements in Mathematics by Dudeney, Henry Ernest

If 4 quantities are in proportion and the second is a mean proportional between the third and fourth, prove that the third will be a mean prop. between the first and second.

From A Review of Algebra by Rivenburg, Romeyn Henry