Probably the ancient Egyptians who discovered that the diagonal of a unit square was not a rational number. And then discovered other such numbers.
There is no single mathematician. It has been known since ancient times that the length of the diagonal of a unit square is sqrt(2) which is irrational.
It was known from ancient times that pi is irrational. However, that fact was proven in 1761 by the Swiss scientist Johann Heinrich Lambert.
Rational numbers, defined as numbers that can be expressed as the quotient of two integers, have been known since ancient times, with their use dating back to at least 2000 BCE in ancient Babylon. The concept of fractions, which are a type of rational number, was also present in ancient Egyptian mathematics. The formal study and classification of rational numbers evolved over centuries, particularly during the development of number theory in the Middle Ages and the Renaissance.
Pythagoras was an ancient philosopher that attributed most of his work to Plato. He however, never went to jail.
They were known to the ancient civilisations. Irrational numbers are supposed to have been discovered by Hippassus of Metapontum, a member of the Pythagorean school in ancient Greece (5th Century BC).
Probably the ancient Egyptians who discovered that the diagonal of a unit square was not a rational number. And then discovered other such numbers.
Yes, Euclid was a philosopher of Ancient Greece.
An ancient Greek mathematician in the era of Pythagoras is said to have been murdered by his fellow secret society members for discovering the (now well-known) proof that square root of 2 is irrational.
Hipparchus, ancient greek philosopher
Plato was the ancient Greek philosopher who was the focus of study for Italian humanists.
Confcius
Socrates.
A philosopher from ancient Egypt.
Confucius.
Homer was a poet and storyteller, not a philosopher - his role was entertainment.
The ancient philosopher known in the Western world as Confucius (whose original name was close to Kung Fu Tse) was relied upon by the government of ancient China.