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

To find a mean proportional between two given straight lines.

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

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

When 5 and 20 are given, x is a mean proportional when in 5, x, 20, 5 is to x as x to 20.

From A Budget of Paradoxes, Volume II by Smith, David Eugene

Define ratio, proportion, mean proportional, third proportional, fourth proportional.

From A Review of Algebra by Rivenburg, Romeyn Henry

Find a mean proportional between 4 and 16; 18 and 50; and 3.

From A Review of Algebra by Rivenburg, Romeyn Henry