Habash al-Hasib al-Marwazi (766–870)

Born 766 CE, died 870 CE.

Ahmad ibn 'Abdallah al-Marwazi, known as Habash al-Hasib (Persian: حبش الحاسب, lit. 'Abyssinian calculator', died c. 869) was a Persian astronomer, geographer, and mathematician from Merv in Khorasan, who discovered the trigonometric ratios tangent, and cotangent. Al-Biruni who cited Habash in his work, expanded his astronomical tables. Habash al-Hasib flourished in Baghdad, and died a centenarian some time between 864 and 874 possibly in Abbasid Samarra. The title "Habash" (Abbyssian) may refer to dark skin color. He worked under two Abbasid caliphs, al-Ma'mun and al-Mu'tasim. Habash al-Hasib developed a trigonometric algorithm to solve problems related to parallax, which was later rediscovered by Johannes Kepler in 1609 and it is now known as Kepler's equation. Habash al-Hasib is the father of the astronomer Abu Ja'far ibn Habash.

Text from the Wikipedia article Habash_al-Hasib, licensed CC BY-SA 4.0.

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Habash al-Hasib al-Marwazi

Ahmad ibn 'Abdallah al-Marwazi, known as Habash al-Hasib (Persian: حبش الحاسب, lit. 'Abyssinian calculator', died c. 869) was a Persian astronomer, geographer, and mathematician from Merv in Khorasan, who discovered the trigonometric ratios tangent, and cotangent. Al-Biruni who cited Habash in his work, expanded his astronomical tables. Habash al-Hasib flourished in Baghdad, and died a centenarian some time between 864 and 874 possibly in Abbasid Samarra. The title "Habash" (Abbyssian) may refer to dark skin color. He worked under two Abbasid caliphs, al-Ma'mun and al-Mu'tasim. Habash al-Hasib developed a trigonometric algorithm to solve problems related to parallax, which was later rediscovered by Johannes Kepler in 1609 and it is now known as Kepler's equation. Habash al-Hasib is the father of the astronomer Abu Ja'far ibn Habash.

Text from the Wikipedia article Habash_al-Hasib (revision 1354592670), licensed CC BY-SA 4.0.