

Online Plane Geometry: Excenters, Excircles, Exradius,
Triangle. Theorems and Problems

Excenter, Excircle of a triangle 
Index 2




Geometry Problem 942.
Triangle, Circles, Circumcircle, Sagitta, Incircle, Excircle, Inradius, Exradius, Metric Relations. 

Geometry Problem
813.
Right Triangle Area, Excircles, Cathetus, Tangency Points, Quadrilateral Area. 

Geometry Problem 766
Triangle, Altitudes, Exradii, Three Exradius, Equal Harmonic Mean. 

Geometry Problem 765
Triangle, Inradius, Exradii, Three Exradius, Harmonic Mean. 

Geometry Problem
720.
Excenter, Intersecting Circles, Angle, Measurement. 

Geometry Problem
707.
Triangle, Excenters, Excircles, Angle Bisectors, Angle, Measurement. 

Geometry Problem 689.
Triangle, Three Excircles, Tangency points, Tangent lines, Concurrent Lines, Mind Map. 

Geometry Problem 687.
Triangle, Three Excircles, Tangency points, Concurrent Lines. 

Geometry Problem 686.
Triangle, Three Excircles, Tangency points, Tangent lines, Semiperimeter, Congruence. 

Geometry Problem 684:
Outer Nagel Point.
Triangle, Excircles, Incircle Tangency points, Concurrent lines, Semiperimeter, Ceva theorem. 

Geometry Problem 683:
Nagel Point.
Triangle, Excircles, Tangency points, Concurrent lines, Semiperimeter, Ceva theorem. 

Geometry Problem 682: Gergonne External Point.
Triangle, Excircle, Tangency points, Concurrent lines, Semiperimeter, Ceva theorem. 

Geometry Problem 624
Triangle, Incenter, Excenter, Incircle, Excircle, Similarity. 

Geometry Problem 626
Triangle, Distance from the Incenter to an Excenter. 

Geometry Problem 623
Triangle, Incenter, Excenter, Incircle, Excircle, Concyclic Points. 

Problem
572.
Right triangle, Median, Circle, Diameter, Excircle, Tangent circles. 

Problem
569.
Quadrilateral, Excircles, Tangency Points, Congruence. 

Problem
568.
Triangle, Excircles, Tangency Point, Congruence. 

Problem
567.
Right triangle, Incircle, Excircle, Collinear tangency points. 

Problem
564.
Complete Quadrilateral, Incenter, Excenter, Concyclic Points, Incircle, Excircle. 

Proposed Problem 419.
Triangle, Cevian, Incircle, Excircle, Inradius, Exradius 

Proposed Problem 380.
Triangle, Excenter, Parallel to a side, Angle, Congruence. 

Proposed Problem 379.
Triangle, Excenter, Parallel to a side, Angle, Congruence. 

Proposed Problem 376.
Triangle, Excenter, Internal and External Angle Bisectors. 

Proposed Problem 375.
Triangle, Excenter, External Angle Bisectors. 

Proposed Problem 320.
Triangle, Circumcircle, Incenter, Excenter, Collinear points. 

Proposed Problem 294.
Right triangle, Circumcenter, Excenter, Hypotenuse, Perpendicular. 

Second
AjimaMalfatti Point
Interactive illustration.
Excenters of a triangle 

Feuerbach Points and NinePoint Circle with interactive
animation, manipulation, and stepbystep construction.
Incenter, Incircle, Excenters, Excircles. 

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

Heron's Formula.
Key facts and
a purely geometric
stepbystep proof.
Incenter, Incircle, Excenter.


Semiperimeter, incircle and excircles of a triangle.


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


Right Triangles, Formulas and Facts
Pythagorean theorem, Similarity, Geometric mean,
hypotenuse, cathetus (legs), semiperimeter, altitude, median,
similar shapes areas, centers, orthocenter, incenter,
incircle, centroid, circumcenter, radius, inradius,
excenters, exradius. 

Feuerbach
Theorem, Acute Triangle illustration


Feuerbach
Theorem, Obtuse Triangle illustration


Feuerbach
Theorem, Right Triangle illustration


Proposed Problem 207. Right Triangle, Hypotenuse, Incenter,
Inradius, Excenter, Exradius relative to the hypotenuse. 

Problem 206. Area of a Right Triangle, Inradius, and
Excenter, Exradius relative to the hypotenuse. 

Proposed Problem 204. Right Triangle, Incircle, Excenters,
Excircles, Inradius, Exradii. 

Proposed Problem 202. Right Triangle, Incircle, Excenters, Excircles
relatives to catheti, Points of Tangency, Exradius, Semiperimeter.


Proposed Problem 200. Right Triangle, Incircle, Excircles, Points of
Tangency, Inradius. 

Proposed Problem 197. Area of a
Triangle, Side, Incircle, Inradius, Excenter, and Exradius. 

Proposed Problem 196. Triangle,
Incircle, Inradius and Exradii Formula. 

Journey to the
Center of a Triangle (1976). Incenter, Circumcenter, Centroid,
Orthocenter.


Proposed Problem 195. Area of a
Triangle, Incircle, Inradius, Excenters, Exradii. 
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