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## Who was Euclid?

Euclid of Alexandria, born around 325 BCE, has been called “the father of geometry”. He studied under Plato in Greece, but settled in Alexandria, Egypt.

Euclid’s famous “The Elements” is a thirteen-volume tome that lays the foundations for geometry and number theory. It contains the famous “Five Postulates” of geometry. By changing only the fifth postulate in **Book I**, Euclidean geometry (“plane geometry”) can be transformed into spherical geometry or other non-Euclidean forms.

In “The Elements”, **Book X** deals with irrational numbers.

Euclid died about 265 BCE.

**References**:

Clegg, Brian. “The Dangerous Ratio“. Enriching Mathematics. (Nov. & Dec. 2004). Accessed Sept. 17, 2011.

Foster, T.L. “Euclid of Alexandria“. Accessed Sept. 18, 2011.

Joyce, D.E. “Euclid’s Elements, Book I”. Clark University. Accessed Sept. 18, 2011.

Joyce, D.E. “Euclid’s Elements, Book X”. Clark University. Accessed Sept. 19, 2011.

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