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  2. Thales's theorem - Wikipedia

    en.wikipedia.org/wiki/Thales's_theorem

    In geometry, Thales's theorem states that if A, B, and C are distinct points on a circle where the line AC is a diameter, the angle ∠ ABC is a right angle. Thales's theorem is a special case of the inscribed angle theorem and is mentioned and proved as part of the 31st proposition in the third book of Euclid's Elements. [1]

  3. Power of a point - Wikipedia

    en.wikipedia.org/wiki/Power_of_a_point

    Due to the Pythagorean theorem the number () has the simple geometric meanings shown in the diagram: For a point outside the circle () is the squared tangential distance | | of point to the circle . Points with equal power, isolines of Π ( P ) {\displaystyle \Pi (P)} , are circles concentric to circle c {\displaystyle c} .

  4. Descartes' theorem - Wikipedia

    en.wikipedia.org/wiki/Descartes'_theorem

    Each circle is labeled by an integer i, its position in the sequence; it has radius ρ i and curvature ρ −i. When the four radii of the circles in Descartes' theorem are assumed to be in a geometric progression with ratio , the curvatures are also in the same progression (in reverse). Plugging this ratio into the theorem gives the equation

  5. List of incomplete proofs - Wikipedia

    en.wikipedia.org/wiki/List_of_incomplete_proofs

    In 1961, Jan-Erik Roos published an incorrect theorem about the vanishing of the first derived functor of the inverse limit functor under certain general conditions. [16] However, in 2002, Amnon Neeman constructed a counterexample. [17] Roos showed in 2006 that the theorem holds if one adds the assumption that the category has a set of ...

  6. Category:Theorems about circles - Wikipedia

    en.wikipedia.org/.../Category:Theorems_about_circles

    Download as PDF; Printable version; In other projects Wikidata item; ... Pages in category "Theorems about circles" The following 21 pages are in this category, out ...

  7. Spherical trigonometry - Wikipedia

    en.wikipedia.org/wiki/Spherical_trigonometry

    Consider the great circle that contains the side BC. This great circle is defined by the intersection of a diametral plane with the surface. Draw the normal to that plane at the centre: it intersects the surface at two points and the point that is on the same side of the plane as A is (conventionally) termed the pole of A and it is denoted by A'.

  8. Circle theorem - Wikipedia

    en.wikipedia.org/wiki/Circle_theorem

    Circle theorem may refer to: Any of many theorems related to the circle; often taught as a group in GCSE mathematics. These include: Inscribed angle theorem. Thales' theorem, if A, B and C are points on a circle where the line AC is a diameter of the circle, then the angle ∠ABC is a right angle. Alternate segment theorem. Ptolemy's theorem.

  9. List of theorems - Wikipedia

    en.wikipedia.org/wiki/List_of_theorems

    This is a list of notable theorems. Lists of theorems and similar statements include: List of algebras; List of algorithms; List of axioms; List of conjectures; List of data structures; List of derivatives and integrals in alternative calculi; List of equations; List of fundamental theorems; List of hypotheses; List of inequalities; Lists of ...