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Three quantities are in proportion when the first has the same ratio to the second, that the second has to the third ; and then the middle term is said to be a mean proportional between the other two.
The Elements of Algebra - Page 225
by Elias Loomis - 1856 - 268 pages

## Elements of Geometry: Containing the First Six Books of Euclid, with a ...

John Playfair - Mathematics - 1806 - 320 pages
...second the same ratio that the third has to the fourth. VI. Magnitudes are said to be proportionals, when the first has the same ratio to the second that the third has to the fourth ; and the third to the fourth the same ratio which the fifth has to the sixth,...

## Elements of Geometry: Containing the First Six Books of Euclid, with a ...

John Playfair - Circle-squaring - 1819 - 350 pages
...second the same ratio that the third has to the fourth. VI. Magnitudes are said to be proportionals, when the first has the same ratio to the second that the third has to the fourth ; and the third to the fourth the same ratio which the fifth Las to the sixth,...

## Elements of Geometry and Trigonometry

Adrien Marie Legendre - Geometry - 1836 - 394 pages
...last is said to be a fourth proportional to the other three taken in order. 4. Three quantities are in proportion, when the first has the same ratio to...said to be a mean proportional between the other two. 5. Magnitudes arc said to be in proportion by inversion, or inversely, when the consequents are taken...

## Elements of Plane Geometry According to Euclid

Andrew Bell, Robert Simson - Euclid's Elements - 1837 - 290 pages
...second the same ratio that the third has to the fourth. 11. Magnitudes are said to be proportionals, when the first has the same ratio to the second that the third has to the fourth ; and the third to the fourth the same ratio which the fifth has to the sixth,...

## Elements of Algebra

Algebra - 1838 - 372 pages
...last is said to be a fourth proportional to the other three taken in order. 171. Three quantities are in proportion when the first has the same ratio to...said to be a mean proportional between the other two. 172. Quantities are said to be in proportion fay inversion, or inversely, when the consequents are...

## First Lessons in Algebra: Embracing the Elements of the Science

Charles Davies - Algebra - 1839 - 264 pages
...what are the first and third called ? What the second and fourth ? • 1 47 . Three quantities are in proportion when the first has the same ratio to...mean proportional between the other two. For example, 3 : 6 : : 6 : 12; and 6 is a mean proportional between 3 and 12. 148. Quantities are said to be in...

## First Lessons in Algebra: Embracing the Elements of the Science

Charles Davies - Algebra - 1839 - 272 pages
...quantities, what are the first and third called 1 What the second and fourth 1 1 47 . Three quantities are in proportion when the first has the same ratio to the second that the second has to the tliird ; and then the middle term is said to be a mean proportional between the other two. For example,...

## Elementary Algebra: Embracing the First Principles of the Science

Charles Davies - Algebra - 1842 - 284 pages
...quantities, what are the first and third called ? What the second and fourth * 1 47 . Three quantities are in proportion when the first has the same ratio to...mean proportional between the other two. For example, 3 : 6 : : 6 : 12; and 6 is a mean proportional between 3 and 12. 148. Quantities are said to be in...