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If the means of the geometric proportion are equal, and the rightmost extreme is equal to the difference between the leftmost extreme and a mean, then such a proportion is called harmonic: [6]: =: (). In this case the ratio : is called golden ratio.
In mathematics, two quantities are in the golden ratio if their ratio is the same as the ratio of their sum to the larger of the two quantities. Expressed algebraically, for quantities a {\displaystyle a} and b {\displaystyle b} with a > b > 0 {\displaystyle a>b>0} , a {\displaystyle a} is in a golden ratio to ...
The ratio of width to height of standard-definition television. In mathematics, a ratio (/ ˈ r eɪ ʃ (i) oʊ /) shows how many times one number contains another. For example, if there are eight oranges and six lemons in a bowl of fruit, then the ratio of oranges to lemons is eight to six (that is, 8:6, which is equivalent to the ratio 4:3).
Divina proportione (15th century Italian for Divine proportion), later also called De divina proportione (converting the Italian title into a Latin one) is a book on mathematics written by Luca Pacioli and illustrated by Leonardo da Vinci, completed by February 9th, 1498 [1] in Milan and first printed in 1509. [2]
See also: Positive real numbers § Ratio scale. The ratio type takes its name from the fact that measurement is the estimation of the ratio between a magnitude of a continuous quantity and a unit of measurement of the same kind (Michell, 1997, 1999). Most measurement in the physical sciences and engineering is done on ratio scales.
It has been suggested that the ideal human figure has its navel at the golden ratio (, about 1.618), dividing the body in the ratio of 0.618 to 0.382 (soles of feet to navel:navel to top of head) (1 ⁄ is -1, about 0.618) and Leonardo da Vinci's Vitruvian Man is cited as evidence. [23]
The first two creases divide the square into a silver gnomon with angles in the ratios 5 : 2 : 1, between two right triangles with angles in ratios 4 : 2 : 2 (left) and 4 : 3 : 1 (right). The unit angle is equal to 22.5 degrees.
Real numbers were called "proportions", being the ratios of two lengths, or equivalently being measures of a length in terms of another length, called unit length. Two lengths are "commensurable", if there is a unit in which they are both measured by integers, that is, in modern terminology, if their ratio is a rational number .