
Circumcenter/Circumcircle 
Index 5




Proposed Problem 138.
Circumcenter.
Nagel's Theorem, Orthic Triangle, Altitudes, Circumradius,
Perpendicular. 

Proposed Problem 94.
Circumcenters.
Similar Triangles, Circumcircles, Circumradii. 

Proposed Problem 93.
Circumcenters.
Similar Triangles, Circumcircles, Parallelogram. 

Proposed Problem 92.
Circumcenters.
Similar Triangles, Circumcircles, Circumradii, Parallel. 

Proposed Problem 86. Circumcenter
of the intouch triangle.
Intouch and Extouch Triangles, Areas. 

Intouch and Extouch Triangles. Puzzle cut: 20 Piece Classic
Based on Proposed Problem 86. 

Proposed Problem 83.
Circumcenter.
Area of the Excircle Contact Triangle, exradius, circumradius. 

Proposed Problem 82.
Circumcenter.
Area of the Contact Triangle, inradius, circumradius. 

Proposed Problem 81.
Circumcenter.
Area of a triangle, side, inradius, circumradius. 

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


Miquel's
Pentagram with Dynamic Geometry. Circumcenters.
You can alter the pentagram dynamically in order to test and
prove (or disproved) conjectures and gain mathematical insight that is
less readily available with static drawings by hand. 

Miquel's Pentagram Theorem
Interactive proof with animation and key theorems.


Adams' Circle
Theorem. Circumcenter of
the contact triangle


Lemoine Theorem.
Circumcenter. 

Sawayama Thebault's
theorem. Circumcenter. 

Circulo de los Nueve Puntos: Spanish version.
NinePoint Center, NinePoint Circle, Euler Line (English
version) .
Interactive illustration.


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


The Bevan Point: Puzzle
The circumcenter of the excentral triangle. 

Proposed Problem 248.
Napoleon's Theorem III. Inner and outer Napoleon triangles, Area. 

Proposed Problem 247.
Napoleon's Theorem II. Internal Equilateral triangles. Inner Napoleon
triangle.


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