Introduction

The first person to write proofs was the Greek mathematician Thales in the 6th century B.C. Thales is known as the Father of Greek Mathematics. He is known as the first of the Seven Wise Men of Greece
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Thales

He is credited with at least five theorems:
1) diameters bisect circles
2) base angles in isosceles triangles are equal
3) vertical angles are equal
4) angles inscribed in a semicircle are right and
5) ASA triangle congruence

Leibniz

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Leibniz (1646 â€“1716) introduced the symbol for congruence ~ in manuscript

In 1824 Carl Brandan (1774-1825) used the modern congruent symbol

â‰… in Euclid's Elements.