Triangle Centers  Table of
Content 4




Proposed Problem 79: Triangle.
Similarity, Altitudes, Orthocenter, Incircles, Inradii. 

Interactive
Orthopole of a Triangle: Using
TracenPoche Dynamic Geometry Software,
Online StepbyStep construction, manipulation, and animation. 

Morley's Triangle & Center: with interactive animation and
manipulation.


Schiffler Point: Four Euler Lines with interactive animation and
manipulation.


Proposed Problem 68: Triangle, Incircle, Inradius, Tangent, Similarity.


Proposed Problem 67: Triangle, Circumcircle, Angles, Cyclic
Quadrilateral.


Proposed Problem 66: Triangle, Excircle, Tangents, Geometric Mean.


Proposed Problem 64: Triangle, Incircle, Transversal. 

Incenter, Excenter, Incircle, Excircle Using TracenPoche Dynamic
Software
StepbyStep construction, Manipulation, and animation. 

Three Tangent Circles Theorem Using TracenPoche Dynamic Software
StepbyStep construction, Manipulation, and animation. 

Sangaku Geometry Theorem: Cyclic Quadrilateral.
Inradii, Rectangle. 

Sangaku Problem (An Old Japanese Theorem).
Inradii, Carnot's theorem. 

Triangle Centers. Word find
puzzle. 

Proposed Problem 52: Triangle, angles, incircle.


Feuerbach Theorem
One of the most striking theorems in triangle geometry. 

Feuerbach Points and NinePoint Circle with interactive
animation, manipulation, and stepbystep construction. 

Feuerbach
Point Facts


Feuerbach
Theorem, Acute Triangle illustration


Feuerbach
Theorem, Obtuse Triangle illustration


Feuerbach
Theorem, Right Triangle illustration


Proposed Problem
51: Fagnano's Problem
Inscribed Triangle with the Minimum Perimeter.


Proposed Problem 40.
Triangle, Incenter, Excenter, Angles 80, 40, Distances. 

Proposed
Problem 40. Geometry Help.


Proposed Problem 39.
Triangle, Incircle, Bisector, Cyclic Quadrilateral and angles. 

Proposed Problem 39 Geometry Help.
Facts you should know for the proposed problem 39. 

Proposed
Problem 38.
Right Triangle, altitude, incircles, incenters, and angles. 

Proposed
Problem 37.
Right Triangle, altitude, incircles, incenters, and orthocenter. 

Proposed
Problem 36.
Right Triangle, altitude, incircles and inradii. 

Lemoine Theorem 

Triangle and Squares
17


Triangle and Squares
16


Sawayama Thebault's
theorem 

Proposed Problem
34.
Right triangle, cevian, incircles, tangents and inradius. 