Theodorus of Alexandria

Theodorus of Alexandria was an ancient Greek mathematician from around the 5th century BCE. He is known for his work in geometry and mathematical theory, particularly for proving that certain square roots, like √3 and √5, are irrational—meaning they cannot be expressed as a simple fraction. Theodorus contributed to the study of irrational numbers and was associated with the Platonic Academy. His work laid foundational principles that influenced later mathematicians in understanding the nature of numbers and geometric proportions, highlighting the distinction between rational and irrational quantities.