Zenodorus (Greek:Ζηνόδωρος; c. 200 – c. 140 BC) was an ancientGreek mathematician.

Little is known about the life of Zenodorus, although he may have befriendedPhilonides and made two trips toAthens, as described in Philonides' biography. From the style of his writing, it is known that he lived not much later thanArchimedes.

He is mentioned inDiocles'On Burning Mirrors:

And when Zenodorus the astronomer came down toArcadia and was introduced to us, he asked us how to find a mirror surface such that when it is placed facing the sun the rays reflected from it meet a point and thus cause burning.^[1]

Zenodorus is known for authoring the treatiseOnisoperimetric figures, now lost. Many of its propositions are known fromTheon of Alexandria's commentary onPtolemy'sSyntaxis. In hisOn isoperimetric figures, Zenodorus studies the areas and perimeters of different geometric figures. The most important propositions proved by him are that,

1. Of all regular polygons of equal perimeter, that is the greatest in area which has the most angles.
2. A circle is greater than any regular polygon of equal contour.
3. Of all polygons of the same number of sides and equal perimeter the equilateral and equiangular polygon is the greatest in area.
4. Of all solid figures the surfaces of which are equal, the sphere is the greatest in solid content..^[2][3]

• Heath, Thomas Little (1981).A History of Greek Mathematics, Volume II. Dover publications.ISBN 0-486-24074-6.
• Morris Kline,Mathematical Thought From Ancient to Modern Times, Oxford University Press, 1972.
• G. J. Toomer,Diocles On Burning Mirrors, Sources in the History of Mathematics and the Physical Sciences 1 (New York, 1976).

• O'Connor, John J.;Robertson, Edmund F.,"Zenodorus (mathematician)",MacTutor History of Mathematics Archive,University of St Andrews
• History of the Isoperimetric Problem atConvergence

• Ancient Greek geometers
• 200s BC births
• 140s BC deaths
• 2nd-century BC Greek mathematicians

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