 | Charles Davies - Algebra - 1889 - 330 pages
...equality between two equal ratios. Thus, b ^ d a c' is n proportion, expressing the fact that the ratio ol a to b is equal to the ratio of c to d. This proportion may also be written thus, a : b : : c : d. In either case, the proportion is read,... | |
 | Walter William Rouse Ball - Mathematics - 1890 - 512 pages
...proportion is equal to the product of the means. For if a, b, c, d be in proportion, then, by definition, the ratio of a to b is equal to the ratio of c to d. That is, a _ c b~d" Multiply each side by bd, .'. ad = be. 300. Conversely, if four quantities a, b,... | |
 | Webster Wells - Algebra - 1890 - 560 pages
...of a to b is -; and it is also expressed a: b. 377. A Proportion is an equality of ratios. Thus, if the ratio of a to b is equal to the ratio of c to d, they form a proportion, which may be written in either of the forms : a:b = c:d, - = -, or a : b :... | |
 | James Morford Taylor - Algebra - 1893 - 358 pages
...incommensurable ratio. 214. Proportion. Four numbers, a, b, c, d, are said to be in proportion, when the ratio of a to b is equal to the ratio of с to d. The proportion is written in the form - = -, a : 6 = с : d, or a : b : : с : d, and is read... | |
 | Henry Martyn Taylor - 1893 - 486 pages
...number to the first number. It A, B be two magnitudes such that »» times A is equal to n times It, the ratio of A to B is equal to the ratio of n to HI. Similarly, if m times A be greater than n times /.', the ratio of A to B is greater than that... | |
 | Webster Wells - Geometry - 1894 - 398 pages
...POLYGONS. DEFINITIONS. 227. A Proportion is a statement that two ratios are equal. The statement that the ratio of a to b is equal to the ratio of c to d, may be written in either of the forms a:b — c: d, or - = -. bd ^ Of C 39? The first and fourth terms... | |
 | John Macnie - Geometry - 1895 - 390 pages
...proportion. Thus each of the equalities A : B = C : D, - = —, expresses a proportion that may be 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. 229. The first and fourth terms of a proportion are called... | |
 | Henry Martyn Taylor - Euclid's Elements - 1895 - 708 pages
...second number to the first number. If A, B be two magnitudes such that m times A is equal to n times B, the ratio of A to B is equal to the ratio of n to m. Similarly, if m times A be greater than n times B, the ratio of A to B is greater than that... | |
 | George Albert Wentworth - Algebra - 1896 - 344 pages
...proportion. 340. If the ratios a : b and c : d form a proportion, the proportion is written a:b = c:d, and is read the ratio of a to b is equal to the ratio of c to d ; or a : b : : c : d, and is read a is to b in the same ratio as c is to d. The first and last terms,... | |
 | George Albert Wentworth, George Anthony Hill - Geometry - 1896 - 152 pages
...Circles are circles having the same centre. 84. Proportionals are four quantities, a, b, c, d, such that the ratio of a to b is equal to the ratio of c to d; that is, such that a : b = c : d. The quantity d is called the fourth proportional to a, b, and c.... | |
| |
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. 
