Online Geometry: Triangle Centers, Theorems and Problems Index, Page 3

Triangle Centers - Table of Content 3

Proposed Problem 156. Triangle, Circumradius, Exradius, Chord, Secant line.  

Proposed Problem 155. Euler's Theorem: Distance from the Incenter to the Circumcenter.  

Proposed Problem 154. Triangle, Inradius, Circumradius, Chord.

Proposed Problem 145. Four Triangles, Incircle, Tangent and Parallel to Side, Incenters, Circumcenters.  

Proposed Problem 144. Four Triangles, Incircle, Tangent and Parallel to Side, Inradii.

Proposed Problem 143. Four Triangles, Incircle, Tangent and Parallel to Side, Circumradii.

Proposed Problem 142. Four Triangles, Incircle, Tangent and Parallel to Side, Areas.  

Proposed Problem 141. Triangle, Incircle, Tangent , Parallel, Perimeters.

Proposed Problem 140. Triangle, Excircle, Tangent, Semiperimeter.

Proposed Problem 139. Triangle Area, Orthic Triangle, Semiperimeter, Circumradius.  

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

Proposed Problem 137. Orthic Triangle, Altitudes, Perpendicular, Incircle, Collinear Points, Parallelogram.  

Proposed Problem 136. Orthic Triangle, Altitudes, Perpendicular, Concyclic Points.  

Proposed Problem 135. Orthic Triangle, Altitudes, Perpendicular, Parallel  

Proposed Problem 134. Orthic Triangle, Altitudes, Angle Bisectors, Orthocenter, Incenter.  

Interactive Gergonne Line and Nobbs Points. Dynamic Geometry.
Step-by-Step construction, Manipulation, and animation.

Triangle, Medians, Six Circumcenters Concyclic. Dynamic Geometry.
Step-by-Step construction, Manipulation, and animation.
Prove proposition.

Triangle: Incircle, Perpendicular, Angle Bisector. Dynamic Geometry.
Step-by-Step construction, Manipulation, and animation.
Prove proposition.

Proposed Problem 133. Triangle, Angle Bisectors, Collinear Points.

Proposed Problem 132.
Triangle, 60 degree, Orthocenter, Congruence, Midpoint.
 

Triangle with the bisectors of the exterior angles. Collinearity. Key concept: Menelaus Theorem.
 

Proposed Problem 128. Incenter of a Triangle, Angle Bisectors, Sum of Ratios.

Proposed Problem 127. Centroid and Incenter of a Triangle, Parallel, Proportions.

Proposed Problem 126. Incenter of Triangle, Angle Bisector, Proportions.

Proposed Problem 120. Area of triangle, incenter, excircles, tangent.

Proposed Problem 119. Area of triangle, incenter, excircle, tangent.

Proposed Problem 118. Area of triangle, incenter, excenter, tangent.

Proposed Problem 117. Area of triangle, incenter, excircles, tangent.

Proposed Problem 116. Area of triangle, excircles, tangent.

Proposed Problem 115. Area of triangle, excircles, tangent.

Proposed Problem 114. Area of triangle, incircle, excircle.

Proposed Problem 113. Area of triangle, incircle, excircle.

Complete Quadrilateral: Ortholine-Steiner Line.
Using TracenPoche Dynamic Software
Step-by-Step construction, Manipulation, and animation

Proposed Problem 96. Similar Triangles, Incenters, Parallelogram.

Proposed Problem 95. Similar Triangles, Inradii, Parallel.

Proposed Problem 94. Similar Triangles, Circumcircles, Circumradii.

Proposed Problem 93. Similar Triangles, Circumcircles, Parallelogram.

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

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

Proposed Problem 86. Intouch and Extouch Triangles, Areas.

Contact Triangles. Puzzle cut: 22 Piece Polygons
Based on Proposed Problem 85.

Proposed Problem 85. Contact Triangles Areas, Incircle, Excircle.

Proposed Problem 84. Contact Triangles Areas, Incircle, Excircle, Inradius, Exradius.

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

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

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

Proposed Problem 80. Area of a triangle, side, incircle, inradius.