Mathematician:Oenopides of Chios

Mathematician

Mathematician, geometer and astronomer.

Little is known about him except that he came from the island of Chios, and is generally believed to have lived and worked in Athens in his youth.

Estimated the tilt of the Earth's axis with respect to the ecliptic as $24^\circ$.

May have introduced the rule that all geometric constructions must be done with a straightedge and compass.

Nationality

Greek

History

• Born: c. 490 BCE, Chios (now Khios), Greece
• Died: c. 420 BCE

Theorems and Definitions

• Compass and Straightedge Construction

• Proposition $12$ of Book $\text{I} $: Perpendicular through Given Point in Euclid's The Elements
• Proposition $23$ of Book $\text{I} $: Construction of Equal Angle in Euclid's The Elements

Sources

• John J. O'Connor and Edmund F. Robertson: "Oenopides of Chios": MacTutor History of Mathematics archive