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Circles: Table of Content
(Page 1 of 5)
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122. |
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Bandurria is the oldest Peruvian archaeological site, says expert
Bandurria may rival Caral as oldest citadel in Americas.
Satellite View: circular ceremonial center |
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121. |
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Eight-Point Circle Theorem

Step-by-Step construction, Manipulation, and animation. |
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120. |
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Proposed Problem
100. Circle Area, Archimedes' Book of Lemmas.
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119. |
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Proposed Problem 99: Circle Area, General Extension to Pythagoras' Theorem.
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118. |
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Incircles or inscribed circles.
Proposed Problem
96. Similar Triangles, Incenters, Parallelogram.
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117. |
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Incircles or inscribed circles.
Proposed Problem
95. Similar Triangles, Inradii,
Parallel.  |
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116. |
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Circumcircles or circumscribed circle
Proposed Problem
94. Similar Triangles, Circumcircles,
Circumradii.  |
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115. |
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Circumcircles or circumscribed circle
Proposed Problem
93. Similar Triangles, Circumcircles, Parallelogram.
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114. |
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Circumcircles or circumscribed circle
Proposed Problem
92. Similar Triangles, Circumcircles, Circumradii, Parallel.
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113. |
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Intouch and Extouch Triangles.
Puzzle cut: 20 Piece Classic

Based on Proposed Problem 86. |
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112. |
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Proposed Problem
86. Intouch and Extouch Triangles, Areas.
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111. |
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Taylor Circle Theorem Using TracenPoche Dynamic Software
Step-by-Step construction, Manipulation, and animation.
Henry Martyn Taylor and the blind student of mathematics
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110. |
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Proposed Problem
85. Contact Triangles Areas, Incircle, Excircle.
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109. |
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Proposed Problem
84. Contact Triangles Areas, Incircle, Excircle, Inradius, Exradius.
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108. |
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Proposed Problem
83. Area of the Excircle Contact
Triangle, exradius, circumradius.
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107. |
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Proposed Problem
82. Area of the Contact
Triangle,
inradius, circumradius.
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106. |
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Proposed Problem
81. Area of a triangle,
side, inradius, circumradius.
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105. |
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Proposed Problem
80. Area of a triangle,
side, incircle, inradius.  |
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104. |
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Proposed Problem
79: Triangle.
Similarity, Altitudes, Orthocenter, Incircles, Inradii.
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103. |
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Proposed Problem
78: Angles of a Circle.
Perpendicular and parallel
lines, Midpoint, Diameter, Chord, Cyclic quadrilateral, Congruence.
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102. |
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Proposed Problem
77: Angles of a Circle. Parallel
lines, Cyclic quadrilateral.
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101. |
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I have used
Geometry Expressions, the world's first Interactive Symbolic
Geometry System, to visualize the Archimedean Twins and check out a
variety of conjectures.
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100. |
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Proposed Problem
76: Area of a Circle. Square,
Circle, Circular Sector.
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99. |
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Proposed Problem
74: Three Intersecting Circles. Cyclic
quadrilateral, Angles.

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98. |
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Proposed Problem
73: Three Intersecting Circles. Cyclic
quadrilateral.

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97. |
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Proposed Problem
72: Intersecting Circles. Cyclic
quadrilateral, Chords, Parallel.

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96. |
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Proposed Problem
71: Cyclic Quadrilateral.

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95. |
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Schiffler Point: Four Euler Lines with interactive animation and
manipulation.
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94. |
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Feuerbach Points and Nine-Point Circle with interactive
animation, manipulation, and step-by-step construction.
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93. |
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Incenter, Excenter, Incircle, Excircle Using TracenPoche Dynamic Software
Step-by-Step construction, Manipulation, and animation. |
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92. |
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Four Circles
Theorem Using TracenPoche Dynamic Software
Step-by-Step construction, Manipulation, and animation. |
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91. |
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Three
Tangent Circles
Theorem Using TracenPoche Dynamic Software
Step-by-Step construction, Manipulation, and animation. |
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90. |
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Three Circles
Theorem Using TracenPoche Dynamic Software |
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89. |
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Proposed Problem
68: Triangle, Incircle, Inradius, Tangent, Similarity.
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88. |
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Crop Circles
and Complexity
Crop Circles
and Sacred Geometry
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87. |
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Proposed Problem
67: Triangle, Circumcircle, Angles, Cyclic Quadrilateral.
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86. |
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Proposed Problem
66: Triangle, Excircle, Tangents, Geometric Mean.
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85. |
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Sangaku Geometry Theorem: Cyclic Quadrilateral.
Inradii, Rectangle. |
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84. |
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Sangaku Problem (An Old Japanese Theorem).
Inradii, Carnot's theorem. |
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83. |
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Sangaku Geometry Theorem: Three circles and a tangent line. |
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82. |
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Arbelos, Inscribed Circle and Concyclic Points Cyclic
Quadrilateral. |
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81. |
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Proposed Problem
57: Angle bisector, circles Cyclic
Quadrilateral. |
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80. |
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Proposed Problem
56: Angle bisector, circles Parallel
Lines. |
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79. |
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Proposed Problem
55: Angle bisector, circles Cyclic
Quadrilateral. |
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78. |
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Proposed Problem
54: Angle bisector, circles Midpoint of
arc. |
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77. |
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Proposed Problem
53: Angle bisector, circles |
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76. |
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Feuerbach
Theorem
One of the most striking theorems in triangle geometry. |
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75. |
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Feuerbach
Point Facts
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74. |
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Feuerbach
Theorem, Acute Triangle
illustration
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73. |
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Feuerbach
Theorem,
Obtuse Triangle illustration
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72. |
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Hippocrates and Squaring the Circle
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71. |
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Lunes of
Hippocrates 4
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70. |
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Lunes of
Hippocrates 3
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69. |
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Lunes of
Hippocrates 2
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68. |
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Lunes
of Hippocrates 1
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67. |
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Pythagoras and Circle Area
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66. |
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Brahmagupta's Theorem
Cyclic quadrilateral.
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65. |
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Brahmagupta's Corollary
Cyclic quadrilateral.
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64. |
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Brahmagupta's Formula
Area of a cyclic quadrilateral.
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63. |
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Mascheroni Construction with compass
alone. Midpoint of a segment
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62. |
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Sangaku Proposed
Problem 41. "Mickey Mouse."
Three circles, tangents, radii. |
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