Analysis of information sources in references of the Wikipedia article "Geography" in English language version.
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ignored (help)It was Biruni, not Avicenna, who found a way for a single man, at a single moment, to measure the earth's circumference, by trigonometric calculations based on angles measured from a mountaintop and the plain beneath it – thus improving on Eratosthenes' method of sighting the sun simultaneously from two different sites, applied in the ninth century by astronomers of the Khalif al-Ma'mun.
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ignored (help)It was Biruni, not Avicenna, who found a way for a single man, at a single moment, to measure the earth's circumference, by trigonometric calculations based on angles measured from a mountaintop and the plain beneath it – thus improving on Eratosthenes' method of sighting the sun simultaneously from two different sites, applied in the ninth century by astronomers of the Khalif al-Ma'mun.