Linked from

The 65 pages that link to Triangle, each with the reason it gives.

• Equilateral triangleNarrower topic: The equilateral triangle is a special case of this three-sided polygon.

• Heron's formulaNarrower topic: Heron's formula applies to this shape and no other polygon directly.

• Right triangleNarrower topic: A right triangle is a specific kind of triangle distinguished by one angle.

• Law of cosinesNarrower topic: The law applies to the side-angle relationships of any Euclidean triangle.

• Congruence (geometry)Narrower topic: Triangle congruence criteria are among the most-used tools for proving geometric facts.

• CircumcircleNarrower topic: Its three vertices determine the circumcircle.

• CircumcenterNarrower topic: The circumcenter is defined from a triangle’s three vertices.

• IncenterNarrower topic: The incenter is defined for a triangle and depends on its three interior angles.

• Isosceles triangleNarrower topic: An isosceles triangle is a triangle distinguished by equal side lengths.

• Similar trianglesNarrower topic: Similarity compares the angles and side lengths of these basic polygons.

• Ceva's theoremNarrower topic: Ceva's theorem is formulated from its vertices and opposite sides.

• OrthocenterNarrower topic: The orthocenter is defined from the three altitudes of this basic figure.

• Triangle geometryNarrower topic: Its side lengths and angles define the basic objects of triangle geometry.

• IncircleNarrower topic: The incircle is defined by its position relative to a triangle’s three sides.

• Angle bisectorNarrower topic: Its angle bisectors meet at a single point and divide opposite sides proportionally.

• Euler lineNarrower topic: Its centers and their alignment give the Euler line its definition.

• TetrahedronNarrower topic: Each face of a tetrahedron is a triangle.

• Angle bisector theoremNarrower topic: The theorem relates the sides and angles of this basic geometric figure.

• Law of sinesNarrower topic: The law relates the three sides to their three opposite angles.

• Miquel's theoremNarrower topic: The four circles arise as circumcircles of triangles formed by triples of quadrilateral lines.

• Miquel pointNarrower topic: Each defining circle is the circumcircle of a triangle.

• Simson lineNarrower topic: Its vertices define the circumcircle and its three side lines.

• Fermat pointNarrower topic: The Fermat point is defined from the three vertices of this figure.

• Menelaus's theoremNarrower topic: Its three side lines provide the framework for the theorem's points and ratios.

• Scalene triangleNarrower topic: A scalene triangle is one type of triangle, distinguished by its side lengths.

• Napoleon's theoremNarrower topic: The theorem begins with an arbitrary triangle as its base figure.

• Viviani's theoremNarrower topic: The theorem depends on decomposing a triangle into three regions around an interior point.

• Intercept theoremNarrower topic: The theorem's standard construction places a smaller triangle inside a larger one.

• Morley's trisector theoremNarrower topic: The theorem applies to every triangle, regardless of its side lengths or angle sizes.

• Stewart's theoremNarrower topic: Stewart’s theorem is a relation among lengths within a triangle.

• Weitzenböck's inequalityNarrower topic: The inequality is a universal constraint on the measurements of this basic plane figure.

• Exterior angle theoremNarrower topic: The theorem applies to a triangle and one side extended.

• Hadwiger–Finsler inequalityNarrower topic: The inequality applies specifically to these plane figures and their side lengths.

• Apollonius's theoremNarrower topic: Apollonius's theorem is an identity among the lengths in any triangle.

• Midpoint theoremNarrower topic: The result concerns the relationships among the sides of every triangle.

• Barrow's inequalityNarrower topic: The inequality compares distances defined by a triangle’s vertices and sides.

• Bottema's theoremNarrower topic: The theorem’s perpendiculars are built from points on a triangle’s sides.

• Conway circle theoremNarrower topic: The theorem’s six contact points are defined using a triangle’s side lines.

• De Gua's theoremNarrower topic: Every face whose area appears in the theorem is triangular.

• Droz-Farny line theoremNarrower topic: Its sides provide the lines intersected by the perpendiculars.

• Equal Incircles TheoremNarrower topic: The theorem concerns pairs of these figures.

• Erdős–Mordell inequalityNarrower topic: The inequality compares distances within this basic geometric figure.

• Hinge theoremNarrower topic: The theorem compares two triangles sharing equal corresponding side lengths.

• Inverse Pythagorean theoremNarrower topic: The converse applies to triangles whose three side lengths are known.

• Japanese theoremNarrower topic: Each region formed by the diagonals is a triangle whose inradius enters the theorem.

• Japanese theorem for cyclic polygonsNarrower topic: Every region in the theorem’s vertex-based triangulation is a triangle.

• Marden's theoremNarrower topic: The three noncollinear polynomial roots form the triangle that determines the ellipse.

• Mollweide's formulaNarrower topic: Mollweide's formulas apply to the side-angle relationships of this basic figure.

• Monsky's theoremNarrower topic: The pieces in the partition are triangles, measured by their areas.

• Pompeiu's theoremNarrower topic: Pompeiu's theorem concerns when three measured lengths can be the sides of a triangle.