 Four quantities are said to be in proportion when the product of the extremes is equal to that of the means : thus if A multiplied by D, be equal to B multiplied by C, then A is said to be to B as C is to D.  A Treatise of Practical Surveying, ... - Page 23by Robert Gibson - 1808 - 440 pagesFull view - About this book
 | Robert Gibson, James Ryan - Surveying - 1839 - 452 pages
...are called irregular polygons, as an irregular pentagon, hexagon, &e. 49. Four quantities are said 10 be in proportion when the product of the extremes is equal to that of the means i thus if A multiplied by D be equal to B multiplied by C, then A is said to be to B as C is to D.... | |
 | Olinthus Gregory - Euclid's Elements - 1840 - 208 pages
...by equal fractions, be carefully pointed out. (A.) When four numbers are direct proportionals, the product of the extremes is equal to that of the means. Thus: — If then, also, But Cor. Hence ad C whence the rules of proporc — -j- < . . . . . rr 6 I tion in arithmetic.... | |
 | Olinthus Gregory - Euclid's Elements - 1840 - 204 pages
..." y ' since each has the same ratio to unity. (h.~) When four numbers are direct proportionals, the product of the extremes is equal to that of the means. Thus: — __ ad C whence the rules of propor6 1 tion in arithmetic. [Let it be remarked that the ordinary... | |
 | Admiralty - 1845 - 152 pages
...That is, if a : b and c : d be two equal ratios, as represented by the numerical equation — = — ; then a is said to be to b, as c is to d ; or f> d a, b, c, d are proportionals. This proportion is expressed either by a:b::c:d,ora: b=c :... | |
 | Benjamin Naylor - 1850 - 334 pages
...extreme terms, and the second and third are called the means. If four numbers be in proportion, the product of the extremes is equal to that of the means. Thus, 4, 7, 12, 21, are proportionals, and Extremes. Means. 21x4=12x7 If we have three terms of a proportion... | |
 | Royal Military Academy, Woolwich - Mathematics - 1853 - 476 pages
...95. The order of the terms of a proportion may be changed, provided that in the new arrangement the product of the extremes is equal to that of the means. Thus in the proportion 2 :,'!:: l<> : 15, the following arrangements may be made : — 2 : 3::10 : 15 2... | |
 | J L. Ellenberger - 1854 - 338 pages
...several ways, without altering the proportion. The test of all these transformations will be that the product of the extremes is equal to that of the means. Thus, since 6 : 9 = 8 : 12, or ............ t=T8r. it follows that 6 : 8 = 9 : 12\ / $ = T»T, or 12 : 9... | |
 | Moffatt and Paige - 1879 - 248 pages
...are called the extremes, and the second and third the means. When four numbers are in proportion, the product of the extremes is equal to that of the means. Thus in the proportion — 8 : 16 :: 9 : 18 we find that 8 X 18 = 16 x 9 = 144. In the proportion — 9:6::... | |
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