Thales of Miletus is one of the first acknowledged Greek philosophers. An engineer by trade, he was a brilliant mathematician, scientist, and philosopher. Thales developed five theorems of geometry, which are some of the basic theorems we still teach in high school geometry today:

- A circle is bisected by any diameter.

- The base angles of an isosceles triangle are equal.

- The angles between two intersecting straight lines are equal.

- Two triangles are congruent if they have two angles and one side equal.

- An angle in a semicircle is a right angle.

**Thales Theorem**which is closely related to the inscribed angle theorem.**Quote:**“Time is the wisest of all things that are; for it brings everything to light.”Sources:

"Thales."

"Thales of Miletus."

"Thales."

*Wikipedia*. Wikimedia Foundation, 27 June 2014. Web. 29 June 2014. <http://en.wikipedia.org/wiki/Thales>."Thales of Miletus."

*Thales Biography*. University of St. Andrews Scotland, n.d. Web. 29 June 2014. <http://www-history.mcs.st-and.ac.uk/Biographies/Thales.html>