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Habash Al-Hasib
Ahmad ibn 'Abdallah Habash Hasib Marwazi (766 - d. after 869 in Samarra, Iraq ) was a north-eastern Iranian astronomer, geographer, and mathematician from Merv in Khorasan who for the first time described the trigonometric ratios: sine, cosine, tangent and cotangent. He flourished in Baghdad, and died a centenarian after 869. He worked under the Abbasid caliphs al-Ma'mun and al-Mu'tasim. Work He made observations from 100 to 2035, and compiled three astronomical tables: the first were still in the Hindu manner; the second, called the 'tested" tables, were the most important; they are likely identical with the "Ma'munic" or "Arabic" tables and may be a collective work of al-Ma'mun's astronomers; the third, called tables of the Shah, were smaller. Apropos of the solar eclipse of 829, Habash gives us the first instance of a determination of time by an altitude (in this case, of the sun); a method which was generally adopted by Muslim astronomers. In 830, he seems to have intro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Samarra
Samarra ( ar, سَامَرَّاء, ') is a city in Iraq. It stands on the east bank of the Tigris in the Saladin Governorate, north of Baghdad. The city of Samarra was founded by Abbasid Caliph Al-Mutasim for his Turkish professional army of around 3,000 soldiers which grew to tens of thousands later. In 2003 the city had an estimated population of 348,700. During the Iraqi Civil War, Samarra was in the "Sunni Triangle" of resistance. In medieval times, Samarra was the capital of the Abbasid Caliphate and is the only remaining Islamic capital that retains its original plan, architecture and artistic relics. In 2007, UNESCO named Samarra one of its World Heritage Sites. History Prehistoric Samarra The remains of prehistoric Samarra were first excavated between 1911 and 1914 by the German archaeologist Ernst Herzfeld. Samarra became the type site for the Samarra culture. Since 1946, the notebooks, letters, unpublished excavation reports and photographs have been in th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trigonometry
Trigonometry () is a branch of mathematics that studies relationships between side lengths and angles of triangles. The field emerged in the Hellenistic world during the 3rd century BC from applications of geometry to astronomical studies. The Greeks focused on the calculation of chords, while mathematicians in India created the earliest-known tables of values for trigonometric ratios (also called trigonometric functions) such as sine. Throughout history, trigonometry has been applied in areas such as geodesy, surveying, celestial mechanics, and navigation. Trigonometry is known for its many identities. These trigonometric identities are commonly used for rewriting trigonometrical expressions with the aim to simplify an expression, to find a more useful form of an expression, or to solve an equation. History Sumerian astronomers studied angle measure, using a division of circles into 360 degrees. They, and later the Babylonians, studied the ratios of the sides of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ferdinand Wüstenfeld
Heinrich Ferdinand Wüstenfeld (31 July 1808 – 8 February 1899) was a German orientalist, known as a literary historian of Arabic literature, born at Münden, Hanover. He studied theology and oriental languages at Göttingen and Berlin. He taught at Göttingen, becoming a professor there (1842–90). He published many important Arabic texts and valuable works on Arabic history. Writings and translations *Navavi, Liber concinnitatis nominum (1832) * (1833–34) * (1835) *Ibn Challikan, Vitae illustrium virorum (1835–50) *Geschichte der Arabischen Ärzte und Naturforscher (1840) *Navavi, ''Tahdhib al-Asma'', Biographical dictionary of illustrious men (4 bd, 1842–47) The biographical dictionary of illustrious men, chiefly at the beginning of Islamism; now first ed. from the collation of two mss. at Göttingen and Leiden (1842)*Makrizi, Geschichte der Kopten (1846) *Zakariya al-Qazwini, ‘Aja'ib al-makhluqat, Zakarija Ben Muhammed Ben Mahmud el-Cazwini's Kosmographie (2 v ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Pre-modern Iranian Scientists And Scholars
The following is a non-comprehensive list of Iranian scientists, engineers, and scholars who lived from antiquity up until the beginning of the modern age. For the modern era, see List of contemporary Iranian scientists, scholars, and engineers. For mathematicians of any era, see List of Iranian mathematicians. (A person may appear on two lists, e.g. Abū Ja'far al-Khāzin.) A * Abdul Qadir Gilani (12th century) theologian and philosopher * Abu al-Qasim Muqane'i (10th century) physician * Abu Dawood (c. 817–889), Islamic scholar * Abu Hanifa (699–767), Islamic scholar * Abu Said Gorgani (10th century) * 'Adud al-Dawla (936–983), scientific patron * Ahmad ibn Farrokh (12th century), physician * Ahmad ibn 'Imad al-Din (11th century), physician and chemist * Alavi Shirazi (1670–1747), royal physician to Mughal Empire of South Asia * Amuli, Muhammad ibn Mahmud (c. 1300–1352), physician * Abū Ja'far al-Khāzin (900–971), mathematician and astronomer * Ansari, K ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Muslim Scientists
This is a list of Muslim scientists who have contributed significantly to science and civilization in the Islamic Golden Age (i.e. from the 8th century to the 14th century). Astronomers and astrologers * Ibrahim al-Fazari (d. 777) * Muhammad al-Fazari (d. 796 or 806) * Al-Khwarizmi (d. 850) * Sanad ibn Ali (d. 864) * Al-Marwazi (d. 869) * Al-Farghani (d. 870) * Al-Mahani (d. 880) *Abu Ma'shar al-Balkhi (d. 886) * Dīnawarī (d. 896) * Banū Mūsā (d. 9th century) *Abu Sa'id Gorgani (d. 9th century) * Ahmad Nahavandi (d. 9th century) *Al-Nayrizi (d. 922) *Al-Battani (d. 929) *Abū Ja'far al-Khāzin (d. 971) *Abd Al-Rahman Al Sufi (d. 986) * Al-Saghani (d. 990) * Abū al-Wafā' al-Būzjānī (d. 998) * Abu Al-Fadl Harawi (d. 10th century) * Abū Sahl al-Qūhī (d. 1000) *Abu-Mahmud al-Khujandi (d. 1000) * Al-Majriti (d. 1007) *Ibn Yunus (d. 1009) * Kushyar ibn Labban (d. 1029) * Abu Nasr Mansur (d. 1036) * Abu l-Hasan 'Ali (d. 1037) * Ibn Sina (d. 1037) *Ibn al-Haytham (d. 104 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Minute Of Arc
A minute of arc, arcminute (arcmin), arc minute, or minute arc, denoted by the symbol , is a unit of angular measurement equal to of one degree. Since one degree is of a turn (or complete rotation), one minute of arc is of a turn. The nautical mile (nmi) was originally defined as the arc length of a minute of latitude on a spherical Earth, so the actual Earth circumference is very near . A minute of arc is of a radian. A second of arc, arcsecond (arcsec), or arc second, denoted by the symbol , is of an arcminute, of a degree, of a turn, and (about ) of a radian. These units originated in Babylonian astronomy as sexagesimal subdivisions of the degree; they are used in fields that involve very small angles, such as astronomy, optometry, ophthalmology, optics, navigation, land surveying, and marksmanship. To express even smaller angles, standard SI prefixes can be employed; the milliarcsecond (mas) and microarcsecond (μas), for instance, are commonly used in ast ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Degree (angle)
A degree (in full, a degree of arc, arc degree, or arcdegree), usually denoted by ° (the degree symbol), is a measurement of a plane (mathematics), plane angle in which one Turn (geometry), full rotation is 360 degrees. It is not an SI unit—the SI unit of angular measure is the radian—but it is mentioned in the SI Brochure, SI brochure as an Non-SI units mentioned in the SI, accepted unit. Because a full rotation equals 2 radians, one degree is equivalent to radians. History The original motivation for choosing the degree as a unit of rotations and angles is unknown. One theory states that it is related to the fact that 360 is approximately the number of days in a year. Ancient astronomers noticed that the sun, which follows through the ecliptic path over the course of the year, seems to advance in its path by approximately one degree each day. Some ancient calendars, such as the Iranian calendar, Persian calendar and the Babylonian calendar, used 360 days for a year. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radius
In classical geometry, a radius ( : radii) of a circle or sphere is any of the line segments from its center to its perimeter, and in more modern usage, it is also their length. The name comes from the latin ''radius'', meaning ray but also the spoke of a chariot wheel. as a function of axial position ../nowiki>" Spherical coordinates In a spherical coordinate system, the radius describes the distance of a point from a fixed origin. Its position if further defined by the polar angle measured between the radial direction and a fixed zenith direction, and the azimuth angle, the angle between the orthogonal projection of the radial direction on a reference plane that passes through the origin and is orthogonal to the zenith, and a fixed reference direction in that plane. See also *Bend radius *Filling radius in Riemannian geometry *Radius of convergence * Radius of convexity *Radius of curvature *Radius of gyration ''Radius of gyration'' or gyradius of a body about the axis of r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sexagesimal
Sexagesimal, also known as base 60 or sexagenary, is a numeral system with sixty as its base. It originated with the ancient Sumerians in the 3rd millennium BC, was passed down to the ancient Babylonians, and is still used—in a modified form—for measuring time, angles, and geographic coordinates. The number 60, a superior highly composite number, has twelve factors, namely 1, 2, 3, 4, 5, 6, 10, 12, 15, 20, 30, and 60, of which 2, 3, and 5 are prime numbers. With so many factors, many fractions involving sexagesimal numbers are simplified. For example, one hour can be divided evenly into sections of 30 minutes, 20 minutes, 15 minutes, 12 minutes, 10 minutes, 6 minutes, 5 minutes, 4 minutes, 3 minutes, 2 minutes, and 1 minute. 60 is the smallest number that is divisible by every number from 1 to 6; that is, it is the lowest common multiple of 1, 2, 3, 4, 5, and 6. ''In this article, all sexagesimal digits are represented as decimal numbers, except where otherwise noted. For e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Earth Radius
Earth radius (denoted as ''R''🜨 or R_E) is the distance from the center of Earth to a point on or near its surface. Approximating the figure of Earth by an Earth spheroid, the radius ranges from a maximum of nearly (equatorial radius, denoted ''a'') to a minimum of nearly (polar radius, denoted ''b''). A ''nominal Earth radius'' is sometimes used as a unit of measurement in astronomy and geophysics, which is recommended by the International Astronomical Union to be the equatorial value. A globally-average value is usually considered to be with a 0.3% variability (±10 km) for the following reasons. The International Union of Geodesy and Geophysics (IUGG) provides three reference values: the ''mean radius'' (R) of three radii measured at two equator points and a pole; the ''authalic radius'', which is the radius of a sphere with the same surface area (R); and the ''volumetric radius'', which is the radius of a sphere having the same volume as the ellipsoid (R). All three ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diameter
In geometry, a diameter of a circle is any straight line segment that passes through the center of the circle and whose endpoints lie on the circle. It can also be defined as the longest chord of the circle. Both definitions are also valid for the diameter of a sphere. In more modern usage, the length d of a diameter is also called the diameter. In this sense one speaks of diameter rather than diameter (which refers to the line segment itself), because all diameters of a circle or sphere have the same length, this being twice the radius r. :d = 2r \qquad\text\qquad r = \frac. For a convex shape in the plane, the diameter is defined to be the largest distance that can be formed between two opposite parallel lines tangent to its boundary, and the is often defined to be the smallest such distance. Both quantities can be calculated efficiently using rotating calipers. For a curve of constant width such as the Reuleaux triangle, the width and diameter are the same because all ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Circumference
In geometry, the circumference (from Latin ''circumferens'', meaning "carrying around") is the perimeter of a circle or ellipse. That is, the circumference would be the arc length of the circle, as if it were opened up and straightened out to a line segment. More generally, the perimeter is the curve length around any closed figure. Circumference may also refer to the circle itself, that is, the locus corresponding to the edge of a disk. The is the circumference, or length, of any one of its great circles. Circle The circumference of a circle is the distance around it, but if, as in many elementary treatments, distance is defined in terms of straight lines, this cannot be used as a definition. Under these circumstances, the circumference of a circle may be defined as the limit of the perimeters of inscribed regular polygons as the number of sides increases without bound. The term circumference is used when measuring physical objects, as well as when considering abstract g ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
