**Hippocrates of Chios** (Greek : Ἱπποκράτης ὁ Χῖος; c. 470 – c. 410 BC) was an ancient Greek mathematician, geometer, and astronomer.

He was born on the isle of Chios, where he was originally a merchant. After some misadventures (he was robbed by either pirates or fraudulent customs officials) he went to Athens, possibly for litigation, where he became a leading mathematician.

On Chios, Hippocrates may have been a pupil of the mathematician and astronomer Oenopides of Chios. In his mathematical work there probably was some Pythagorean influence too, perhaps via contacts between Chios and the neighboring island of Samos, a center of Pythagorean thinking: Hippocrates has been described as a 'para-Pythagorean', a philosophical 'fellow traveler'. "Reduction" arguments such as * reductio ad absurdum * argument (or proof by contradiction) have been traced to him, as has the use of power to denote the square of a line.^{ [1] }

The major accomplishment of Hippocrates is that he was the first to write a systematically organized geometry textbook, called *Elements* (Στοιχεῖα, *Stoicheia*), that is, basic theorems, or building blocks of mathematical theory. From then on, mathematicians from all over the ancient world could, at least in principle, build on a common framework of basic concepts, methods, and theorems, which stimulated the scientific progress of mathematics.

Only a single, famous fragment of Hippocrates' *Elements* is existent, embedded in the work of Simplicius. In this fragment the area is calculated of some so-called *Hippocratic lunes *— see Lune of Hippocrates. This was part of a research program to achieve the "quadrature of the circle", that is, to calculate the area of the circle, or, equivalently, to construct a square with the same area as a circle. The strategy, apparently, was to divide a circle into a number of crescent-shaped parts. If it were possible to calculate the area of each of those parts, then the area of the circle as a whole would be known too.^{[ citation needed ]} Only much later was it proven (by Ferdinand von Lindemann, in 1882) that this approach had no chance of success, because the factor pi (π) is transcendental. The number π is the ratio of the circumference to the diameter of a circle, and also the ratio of the area to the square of the radius.

In the century after Hippocrates, at least four other mathematicians wrote their own *Elements*, steadily improving terminology and logical structure. In this way, Hippocrates' pioneering work laid the foundation for Euclid's *Elements* (c. 325 BC), which was to remain the standard geometry textbook for many centuries. Hippocrates is believed to have originated the use of letters to refer to the geometric points and figures in a proposition, e.g., "triangle ABC" for a triangle with vertices at points A, B, and C.

Two other contributions by Hippocrates in the field of mathematics are noteworthy. He found a way to tackle the problem of 'duplication of the cube', that is, the problem of how to construct a cube root. Like the quadrature of the circle, this was another of the so-called three great mathematical problems of antiquity. Hippocrates also invented the technique of 'reduction', that is, to transform specific mathematical problems into a more general problem that is easier to solve. The solution to the more general problem then automatically gives a solution to the original problem.

In the field of astronomy, Hippocrates tried to explain the phenomena of comets and the Milky Way. His ideas have not been handed down very clearly, but he probably thought both were optical illusions, the result of refraction of solar light by moisture that was exhaled by, respectively, a putative planet near the Sun, and the stars. The fact that Hippocrates thought that light rays originated in our eyes instead of in the object that is seen, adds to the unfamiliar character of his ideas.

- ↑ W. W. Rouse Ball,
*A Short Account of the History of Mathematics*(1888) p. 36.

**Area** is the quantity that expresses the extent of a two-dimensional figure or shape or planar lamina, in the plane. Surface area is its analog on the two-dimensional surface of a three-dimensional object. Area can be understood as the amount of material with a given thickness that would be necessary to fashion a model of the shape, or the amount of paint necessary to cover the surface with a single coat. It is the two-dimensional analog of the length of a curve or the volume of a solid.

**Euclidean geometry** is a mathematical system attributed to Alexandrian Greek mathematician Euclid, which he described in his textbook on geometry: the *Elements*. Euclid's method consists in assuming a small set of intuitively appealing axioms, and deducing many other propositions (theorems) from these. Although many of Euclid's results had been stated by earlier mathematicians, Euclid was the first to show how these propositions could fit into a comprehensive deductive and logical system. The *Elements* begins with **plane geometry**, still taught in secondary school as the first axiomatic system and the first examples of formal proof. It goes on to the solid geometry of three dimensions. Much of the *Elements* states results of what are now called algebra and number theory, explained in geometrical language.

Geometry arose as the field of knowledge dealing with spatial relationships. Geometry was one of the two fields of pre-modern mathematics, the other being the study of numbers (arithmetic).

**Straightedge and compass construction**, also known as **ruler-and-compass construction** or **classical construction**, is the construction of lengths, angles, and other geometric figures using only an idealized ruler and compass.

**Squaring the circle** is a problem proposed by ancient geometers. It is the challenge of constructing a square with the same area as a given circle by using only a finite number of steps with compass and straightedge. The difficulty of the problem raised the question of whether specified axioms of Euclidean geometry concerning the existence of lines and circles implied the existence of such a square.

**Archytas** was an Ancient Greek philosopher, mathematician, astronomer, statesman, and strategist. He was a scientist of the Pythagorean school and famous for being the reputed founder of mathematical mechanics, as well as a good friend of Plato.

The * Elements* is a mathematical treatise consisting of 13 books attributed to the ancient Greek mathematician Euclid in Alexandria, Ptolemaic Egypt c. 300 BC. It is a collection of definitions, postulates, propositions, and mathematical proofs of the propositions. The books cover plane and solid Euclidean geometry, elementary number theory, and incommensurable lines.

**Pappus of Alexandria** was one of the last great Greek mathematicians of antiquity, known for his *Synagoge* (Συναγωγή) or *Collection*, and for Pappus's hexagon theorem in projective geometry. Nothing is known of his life, other than what can be found in his own writings: that he had a son named Hermodorus, and was a teacher in Alexandria.

In mathematics, a **semicircle** is a one-dimensional locus of points that forms half of a circle. The full arc of a semicircle always measures 180°. It has only one line of symmetry. In non-technical usage, the term "semicircle" is sometimes used to refer to a half-disk, which is a two-dimensional geometric shape that also includes the diameter segment from one end of the arc to the other as well as all the interior points.

In mathematics, **quadrature** is a historical term which means the process of determining area. This term is still used nowadays in the context of differential equations, where "solving an equation by quadrature" means expressing its solution in terms of integrals.

The **method of exhaustion** is a method of finding the area of a shape by inscribing inside it a sequence of polygons whose areas converge to the area of the containing shape. If the sequence is correctly constructed, the difference in area between the *n*th polygon and the containing shape will become arbitrarily small as *n* becomes large. As this difference becomes arbitrarily small, the possible values for the area of the shape are systematically "exhausted" by the lower bound areas successively established by the sequence members.

A **special right triangle** is a right triangle with some regular feature that makes calculations on the triangle easier, or for which simple formulas exist. For example, a right triangle may have angles that form simple relationships, such as 45°–45°–90°. This is called an "angle-based" right triangle. A "side-based" right triangle is one in which the lengths of the sides form ratios of whole numbers, such as 3 : 4 : 5, or of other special numbers such as the golden ratio. Knowing the relationships of the angles or ratios of sides of these special right triangles allows one to quickly calculate various lengths in geometric problems without resorting to more advanced methods.

A **Kepler triangle** is a right triangle with edge lengths in a geometric progression. The ratio of the progression is √*φ*, where *φ* is the golden ratio, and can be written: , or approximately **1 : 1.272 : 1.618**. The squares of the edges of this triangle are also in geometric progression according to the golden ratio itself.

**Thomas Clausen** was a Danish mathematician and astronomer.

A timeline of **algebra** and **geometry**

This is a timeline of pure and applied mathematics history.

In geometry, the **lune of Hippocrates**, named after Hippocrates of Chios, is a lune bounded by arcs of two circles, the smaller of which has as its diameter a chord spanning a right angle on the larger circle. Equivalently, it is a non-convex plane region bounded by one 180-degree circular arc and one 90-degree circular arc. It was the first curved figure to have its exact area calculated mathematically.

In mathematics, the **Pythagorean theorem**, also known as **Pythagoras's theorem**, is a fundamental relation in Euclidean geometry among the three sides of a right triangle. It states that the area of the square whose side is the hypotenuse is equal to the sum of the areas of the squares on the other two sides. This theorem can be written as an equation relating the lengths of the sides *a*, *b* and *c*, often called the "Pythagorean equation":

**Wilbur Richard Knorr** was an American historian of mathematics and a professor in the departments of philosophy and classics at Stanford University. He has been called "one of the most profound and certainly the most provocative historian of Greek mathematics" of the 20th century.

- Ivor Bulmer-Thomas, 'Hippocrates of Chios', in:
*Dictionary of Scientific Biography*, Charles Coulston Gillispie, ed. (18 Volumes, New York 1970–1990) pp. 410–418. - [Axel Anthon] Björnbo, 'Hippokrates', in: Paulys Realencyclopädie der Classischen Altertumswissenschaft, G. Wissowa, ed. (51 Volumes; 1894–1980) Vol. 8 (1913) col. 1780–1801.

Wikiquote has quotations related to: Hippocrates of Chios |

- O'Connor, John J.; Robertson, Edmund F., "Hippocrates of Chios",
*MacTutor History of Mathematics archive*, University of St Andrews . - The Quadrature of the Circle and Hippocrates' Lunes at Convergence
- Mesolabe Compass and Square Roots - Numberphile video explaining Hippocrates' mesolabe compass

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