Books Books
Four quantities are proportional when the ratio of the first to the second is equal to the ratio of the third to the fourth.
Eaton's Elementary Algebra, Designed for the Use of High Schools and Academies - Page 87
by William Frothingham Bradbury - 1875

## Mathematical Dictionary and Cyclopedia of Mathematical Science Comprising ...

Charles Davies, William Guy Peck - Mathematics - 1859 - 622 pages
...the ini'asure of proportion is ratio. Four quantities are in proportion when the ratio of the lir.st to the second is equal to the ratio of the third to the fourth ; this relation is expressed algebraically thus, a. : b : : с : d. This expression is called a proportion...

## Elements of Algebra: On the Basis of M. Bourdon, Embracing Sturm's and ...

Charles Davies - Algebra - 1860 - 412 pages
...changes of value, then a is said to be proportional to b. • 183i Four quantities are in proportion, when the ratio of the first to the second, is equal to the ratio of the third to the fourth. Thus, if the quantities a, 6, c and d, are said to be in propoition. We generally express that these...

## Practical arithmetic for senior classes

Henry G C. Smith - 1863 - 200 pages
...term, 16, is called the Antecedent, and the second, 8, the Consequent. Pour numbers are said to be Proportional when the ratio of the first to the second...is equal to the ratio of the third to the fourth. On examining the four numbers, 14, 8, 35, 20, we find V = i5, or 14 : 8 = 85 : 20, and say 14 is to...

## The Quarterly journal of education and scholastic advertiser

1872 - 398 pages
...8. 15. On comparing Def. 3 with Def. 1, it will be seen that when four quantities are in proportion, the ratio of the first to the second is equal to the ratio of the third to the fourth. Hence we may denote a proportion thus — 3:4 = 6:8 which is read — the ratio 3 to 4 is equal to...

## Elements of Plane and Solid Geometry: And of Plane and Spherical ...

Gerardus Beekman Docharty - Geometry - 1867 - 474 pages
...is £ or f , &c. 79. Proportion is an equality of ratios. Thus, 80. Three quantities are said to be proportional when the ratio of the first to the second is equal to the ratio of the second to the third. As of the three quantities A (2), B (4), C (8), where f=f —^, both the same...

## An Elementary Course of Plane Geometry

Richard Wormell - Geometry, Modern - 1868 - 286 pages
...trouble ourselves to inquire what this unit is. Four lines are in proportion, or are proportionals, when the ratio of the first to the second is equal to the ratio of the third and fourth. Very simple geometrical constructions enable us, as we shall see, to draw four straight...

## A Treatise on Elementary Algebra

James Hamblin Smith - 1869 - 412 pages
...the other product must form the means. 328. Three quantities are said to be in CONTINUED PROPORTION when the ratio of the first to the second is equal to the ratio of the second to the third. Thus a, b, с are in continued proportion if a : b = b : c. . The quantity b is...

## An Elementary Course of Plane Geometry

Richard Wormell - Geometry, Plane - 1870 - 304 pages
...trouble ourselves to inquire what this unit is. Four lines are in proportion, or are proportionals, when the ratio of the first to the second is equal to the ratio of the third and fourth. Very simple geometrical constructions enable us, as we shall see, to draw four straight...