Geometry Tutoring, Tutorial, Tutor: Triangle Centers, Theorems and Problems

Triangle Centers, Visual Index.

Incenter of a triangle. Index.

Excenter. Index.
Excircle, Exradius.

Circumcenter. Index.

Centroid /Barycenter. Index.

Orthocenter Index.

Orthocenter of a triangle, Theorems and Problems - Visual Index.

Circumcircle Index.

Nine-Point Center, Nine-Point Circle, Euler Line. Interactive illustration.
Circumcenter, Centroid, Orthocenter
HTML5 Animation for iPad and Nexus
Adobe Flash Animation.

Gergonne Points Index
Triangle Center

Nagel Points Index
Triangle Center

Lester Circle Theorem.

Gergonne Point Theorem. Concurrency. Interactive proof with animation.
HTML5 Animation for Tablets (iPad, Nexus)
Adobe Flash Animation
Key concept: Ceva's Theorem.

Nagel Point Theorem. Proof.
 

Symmedian (Lemoine) Point
Triangle Center

Geometry Problem 1575: Prove an Angle Bisector in a Triangle Involving an Altitude, Midpoint, and Excircle

Geometry Problem 1568: Concyclicity of Points B, D , H, J in a Triangle ABC with an Incircle and a Tangent Circle.

Geometry Problem 1502.
Right Triangle, Incircle, Inradius, Geometric Mean of 2 Inradii, Angle Bisector, Perpendicular, Tangential Quadrilateral.

Geometry Problem 1492.
Right Triangle, Altitude, Incenters, Angle, Measurement.

Geometry Problem 1491.
Cyclic Quadrilateral, Diagonal, Incircle, Angle, Measurement.

Geometry Problem 1490.
Triangle, Cevian, Incircle, Tangent, Measurement.

Geometry Problem 1489.
Right Triangle, Angle Bisectors, Perpendicular, Measurement.

Geometry Problem 1488.
Right Triangle, Altitude, Incircle, Tangent, Measurement.

Geometry Problem 1487.
Right Triangle, Altitude, Incircle, Tangent, Measurement.

Geometry Problem 1486.
Right Triangle, Altitude, Incircle, Tangent, Measurement.

Geometry Problem 1485.
Triangle, Orthocenter, Altitude, Circle, Diameter, Tangent, Measurement.

Dynamic Geometry 1480.
Japanese Theorem for Cyclic Polygon, Sangaku, Triangulation, Non-intersecting Diagonals, Sum of Inradii, Invariant, Step-by-step Illustration. GeoGebra, iPad.

Dynamic Geometry 1479.
Triangle, Circumcircle, Angle Bisector, Perpendicular Bisector, Chord, Concyclic Points, Parallel Lines,, Step-by-step Illustration. GeoGebra, iPad.

Dynamic Geometry 1478.
Cyclocevian, Reuschle-Terquem Theorem, Concurrent Cevians, Triangle, Circumcircle, Secant line, Step-by-step Illustration. GeoGebra, iPad.

Dynamic Geometry 1477.
Miquel's Pentagram Theorem, Pentagon, Triangle, Circumcircles, Concyclic Points, Step-by-step Illustration. GeoGebra, iPad.

Dynamic Geometry 1473.
Kosnita's Theorem, Triangle, Four Circumcenters, Concurrent Line, Step-by-step Illustration.

Dynamic Geometry 1471.
Equilateral Triangle, Inside/Outside Point, Incenters, Tangency Points, Concurrent Lines, Step-by-step Illustration.

Dynamic Geometry 1469.
Triangle, Circumradius, Inradius, Midpoints, Arcs, Sum of Distances, Step-by-step Illustration.

Dynamic Geometry 1468.
Steiner's Theorem, Triangle, Circumradius, Inradius, Sum of Exradii, Step-by-step Illustration.

Geometry Problem 1458.
Triangle, Incircles, Excircle, Area, Step-by-step Illustration using GeoGebra.

Geometry Problem 1457.
Altitudes, Circles, Similarity, Product of the Inradii Lengths, iPad. Step-by-step illustration using GeoGebra.

Geometry Problem 1456.
Altitudes, Orthic Triangle, Circumcircle, Parallel lines, Similarity, Area, iPad. Step-by-step illustration using GeoGebra.

Geometry Problem 1455.
Nagel Point, Excircles, Incircle, Congruent Segments, iPad. Step-by-step illustration using GeoGebra.

Geometry Problem 903: First Fermat Point.
Post a solution
 

Puzzle: Exeter Point
Triangle, Median, Circumcircle, Concurrent Lines, Euler Line.

Dynamic Geometry: Exeter Point
Triangle, Median, Circumcircle, Concurrent Lines, Euler Line, GeoGebra, HTML5 Animation for Tablets.

Second Fermat Point: Static diagram.
Second Fermat Point: Dynamic diagram.
Triangle, Equilateral triangles, Concurrent lines, GeoGebra, HTML5 Animation for Tablets (iPad, Nexus)

Outer Vecten Point.
 

Morley's Triangle and Center
Triangle Center

Feuerbach Point
Triangle Center

iPad Apps: Apollonius Software. Feuerbach Point. Triangle, Incircle, Nine point circle, Tangent circles, Orthocenter, Midpoint.
Interactive Geometry Software.

Schiffler Point: Euler Lines
Triangle Center

The Bevan Point
The circumcenter of the excentral triangle. Illustration with animation.

Spieker Center
Triangle Center

Ajima-Malfatti Point 2
Triangle Center. Interactive illustration.

Ajima-Malfatti Point 1
Triangle Center. Interactive illustration.

Steiner Point
Triangle Center

Mittenpunkt Point
Triangle Center

Kosnita's Theorem.
Circumcenters, Concurrent lines.

Clawson Point.
Orthic and Extangents Triangles, Concurrent lines.

Clawson Point Puzzle, Geometry for Kids.
22 Piece Polygons

Adams' Circle Theorem
 

Distances between Triangle Centers Index.

Triangle Centers.

Proposed Problem 246.
Napoleon's Theorem I. External Equilateral triangles.

Circulo de los Nueve Puntos: Spanish version.
Interactive illustration.

Puzzle: Euler Line and Nine Point Center

Dynamic Geometry Problem 1447.
Outer Vecten Point. Step-by-step illustration using GeoGebra.

Geometry Problem 1231
Triangle, Orthocenter, Incenter, Circumcenter, Angle Bisector, Center, Circle.