Descartes' theorem (disambiguation)

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In geometry, Descartes' theorem states that, for every four mutually tangent circles, the radii of the circles satisfy a certain quadratic equation.

Descartes' theorem may also refer to:

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In mathematics, analytic geometry, also known as coordinate geometry or Cartesian geometry, is the study of geometry using a coordinate system. This contrasts with synthetic geometry.

Cartesian means of or relating to the French philosopher René Descartes—from his Latinized name Cartesius. It may refer to:

<span class="mw-page-title-main">René Descartes</span> French philosopher, mathematician, and scientist (1596–1650)

René Descartes was a French philosopher, scientist, and mathematician, widely considered a seminal figure in the emergence of modern philosophy and science. Mathematics was paramount to his method of inquiry, and he connected the previously separate fields of geometry and algebra into analytic geometry. Descartes spent much of his working life in the Dutch Republic, initially serving the Dutch States Army, later becoming a central intellectual of the Dutch Golden Age. Although he served a Protestant state and was later counted as a deist by critics, Descartes was Roman Catholic.

A mathematical problem is a problem that can be represented, analyzed, and possibly solved, with the methods of mathematics. This can be a real-world problem, such as computing the orbits of the planets in the solar system, or a problem of a more abstract nature, such as Hilbert's problems. It can also be a problem referring to the nature of mathematics itself, such as Russell's Paradox.

<span class="mw-page-title-main">Pappus of Alexandria</span> 4th century Greek mathematician

Pappus of Alexandria was a Greek mathematician of Late Antiquity known for his Synagoge (Συναγωγή) or Collection, and for Pappus's hexagon theorem in projective geometry. Almost nothing is known about his life except for what can be found in his own writings, many of which are lost. Pappus apparently lived in Alexandria were he worked as a mathematics teacher to higher level students, such one named Hermodorus.

<span class="mw-page-title-main">Descartes' theorem</span> Equation for radii of tangent circles

In geometry, Descartes' theorem states that for every four kissing, or mutually tangent, circles, the radii of the circles satisfy a certain quadratic equation. By solving this equation, one can construct a fourth circle tangent to three given, mutually tangent circles. The theorem is named after René Descartes, who stated it in 1643.

In geometry, the (angular) defect means the failure of some angles to add up to the expected amount of 360° or 180°, when such angles in the Euclidean plane would. The opposite notion is the excess.

<span class="mw-page-title-main">Sangaku</span> Wooden tablets inscribed with geometrical theorems in Edo Japan

Sangaku or san gaku are Japanese geometrical problems or theorems on wooden tablets which were placed as offerings at Shinto shrines or Buddhist temples during the Edo period by members of all social classes.

<span class="mw-page-title-main">Cartesian circle</span> Error in reasoning attributed to René Descartes

The Cartesian circle is an example of fallacious circular reasoning attributed to French philosopher René Descartes. He argued that the existence of God is proven by reliable perception, which is itself guaranteed by God.

In mathematics, Descartes' rule of signs, first described by René Descartes in his work La Géométrie, is a technique for getting information on the number of positive real roots of a polynomial. It asserts that the number of positive roots is at most the number of sign changes in the sequence of polynomial's coefficients, and that the difference between these two numbers is always even. This implies, in particular, that if the number of sign changes is zero or one, then there are exactly zero or one positive roots, respectively.

<span class="mw-page-title-main">Problem of Apollonius</span> Construct circles that are tangent to three given circles in a plane

In Euclidean plane geometry, Apollonius's problem is to construct circles that are tangent to three given circles in a plane (Figure 1). Apollonius of Perga posed and solved this famous problem in his work Ἐπαφαί ; this work has been lost, but a 4th-century AD report of his results by Pappus of Alexandria has survived. Three given circles generically have eight different circles that are tangent to them (Figure 2), a pair of solutions for each way to divide the three given circles in two subsets.

<span class="mw-page-title-main">Pierre de Fermat</span> French mathematician and lawyer

Pierre de Fermat was a French mathematician who is given credit for early developments that led to infinitesimal calculus, including his technique of adequality. In particular, he is recognized for his discovery of an original method of finding the greatest and the smallest ordinates of curved lines, which is analogous to that of differential calculus, then unknown, and his research into number theory. He made notable contributions to analytic geometry, probability, and optics. He is best known for his Fermat's principle for light propagation and his Fermat's Last Theorem in number theory, which he described in a note at the margin of a copy of Diophantus' Arithmetica. He was also a lawyer at the Parlement of Toulouse, France.

In geometry, tangent circles are circles in a common plane that intersect in a single point. There are two types of tangency: internal and external. Many problems and constructions in geometry are related to tangent circles; such problems often have real-life applications such as trilateration and maximizing the use of materials.

<span class="mw-page-title-main">Timeline of calculus and mathematical analysis</span> Summary of advancements in Calculus

A timeline of calculus and mathematical analysis.

This is a timeline of pure and applied mathematics history. It is divided here into three stages, corresponding to stages in the development of mathematical notation: a "rhetorical" stage in which calculations are described purely by words, a "syncopated" stage in which quantities and common algebraic operations are beginning to be represented by symbolic abbreviations, and finally a "symbolic" stage, in which comprehensive notational systems for formulas are the norm.

In mathematics, statistics and elsewhere, sums of squares occur in a number of contexts:

Mechanism is the belief that natural wholes are similar to complicated machines or artifacts, composed of parts lacking any intrinsic relationship to each other.

Circle theorem may refer to: