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To express that the ratio of A to B is equal to the ratio of C to D, we write the quantities thus : A : B : : C : D; and read, A is to B as C to D.
Manual of Geometry and Conic Sections: With Applications to Trigonometry and ... - Page 70
by William Guy Peck - 1876 - 366 pages

## Elements of Plane Geometry

Alan Sanders - Geometry, Modern - 1901 - 260 pages
...proportion is the equality of ratios. " = - is a proportion, and expresses the fact that the ratio of bd a to b is equal to the ratio of c to d. The proportion - = may also be written a : b = c : d and a : b : : c : d. In the proportion a = -, the...

William James Milne - Algebra - 1901 - 464 pages
...lines that form the sign of equality. The proportion a : b = с : d, or о : b : : с : d, is read, the ratio of a to b is equal to the ratio of с to d, or a is to & as с is to d. 322. The antecedents and consequents of the ratios that form a...

## Elements of Plane and Solid Geometry

Alan Sanders - Geometry - 1903 - 392 pages
...proportion is the equality of ratios. = - is a proportion, and expresses the fact that the ratio of 6 d a to b is equal to the ratio of c to d. The proportion - = may also be written a : b = c : d and a : b : : c : d. ' " In the proportion = -, the...

## Plane and Solid Geometry

George Albert Wentworth - Geometry - 1904 - 496 pages
...ac a:b = c:d; a:o ::c:d; - = — • 0 CL This proportion is read, " a is to b as c is to d " ; or " the ratio of a to b is equal to the ratio of c to d." 324. The terms of a proportion are the four quantities compared ; the first and third terms are called...

## Plane and Solid Geometry

Isaac Newton Failor - Geometry - 1906 - 431 pages
...proportion may be written in three different forms ; as, - = -; a:b = c:dy a:b::c:d. Each form is read, " the ratio of a to b is equal to the ratio of c to d ; " or, more briefly, " a is to b as c is to d." 319 The terms of a proportion are the four quantities...

## The First Steps in Algebra

George Albert Wentworth - 1894 - 218 pages
...formed by two equal ratios a : b and c : d may be written in three ways : (1) a : b = c : d (read, the ratio of a to b is equal to the ratio of c to d). (2) a : b : : c : d (read, a is to b as c is to d). tv\ a - c (3) -b~d a and d are the extremes, b...

## Plane and Solid Geometry

Isaac Newton Failor - Geometry - 1906 - 440 pages
...proportion may be written in three different forms ; as, - = -; a:b=c:d; a:b::c:d. bd Each form is read, " the ratio of a to b is equal to the ratio of c to d ; " or, more briefly, " a is to b as c is to d." 319 The terms of a proportion are the four quantities...

## Elementary Algebra

George Albert Wentworth - Algebra - 1906 - 440 pages
...376. If the ratios ct : b and с : d form a proportion, the proportion is written a : b = с : d (read the ratio of a to b is equal to the ratio of с to d), or a:b::c:d (read a is to b in the same ratio as с is to d). The four numbers a, b, c, d...