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If the product of two quantities is equal to the product of two others, either two may be made the extremes of a proportion and the other two the means.
A Text-book of Geometry - Page 128
by George Albert Wentworth - 1888 - 386 pages

## Elements of Algebra: For Colleges, Schools and Private Students

Joseph Ray - Algebra - 1866 - 420 pages
...8, is not a true proportion, since 3X5 is not equal to 2X8. 268. Proposition II.— Conversely, If the product of two quantities is equal to the product of two others, two of them may be made the means, and the other two the extremes of a proportion. Let . ....... bo...

## A Treatise on Elementary Geometry: With Appendices Containing a Collection ...

William Chauvenet - Mathematics - 1872 - 382 pages
...numbers is equal to the square root of their product. 6. Conversely, if the product of two numbers is equal to the product of two others, either two may be made the extremes, and the other two the means, of a proportion. For, if we have given ab' = a'b, then, dividing by bb',...

## An Elementary Geometry

William Frothingham Bradbury - Geometry - 1872 - 124 pages
...equal to the product of the means is merely clearing the equation of fractions. THEOREM II. 141 If the product of two quantities is equal to the product of two others, the factors of either product may be made the extremes, and the factors of the other the means of a...

## An Elementary Geometry and Trigonometry

William Frothingham Bradbury - Geometry - 1872 - 262 pages
...equal to the product of the means is merely clearing the equation of fractions. THEOREM II. 14, If the product of two quantities is equal to the product of two others, the factors of eiIher product may be made the extremes, and the factors of the other the means of a...

## Elements of Geometry and Trigonometry from the Works of A.M. Legendre ...

Charles Davies - Geometry - 1872 - 464 pages
...this case, the square of the mean w equal to the product of the extremes. PROPOSITION II. THEOREM. If the product of two quantities is equal to the product of two other quantit1es, two nf them may be made the means, and the other two the extremes of a proportion....

## A Treatise on Algebra

Elias Loomis - Algebra - 1873 - 396 pages
...: d. Then | = |,Art.292. Multiplying each of these equals by bd, we have ad=bc. 300. Conversely, if the product of two quantities is equal to the product of two other quantities, the first two may be made the extremes, and the other two the means of a proportion....

## Elements of Geometry and Trigonometry: From the Works of A.M. Legendre

Adrien Marie Legendre - Geometry - 1874 - 500 pages
...this case, the square of the mean is equal to the product of the extremes. PROPOSITION n. THEOREM. If the product of two quantities is equal to the product of two other quantities, two of them may be made the means, and the other two the extremes of a proportion....

## Manual of Algebra

William Guy Peck - Algebra - 1875 - 348 pages
...Conversely, if we divide both members of (2) by ca, we have, - = -; or, a : b :: c : d; hence, ac If the product of two quantities is equal to the product of two other quantities, the first two may be made the means, and the second two the extremes, of a proportion....