College Geometry Online, eLearning

Online Geometry: Congruence, Rotation, Translation, Reflection - Page 1

Congruence, Translation, Rotation, Reflection

Euclid's Elements 23 definitions

Euclid's Elements Book I, 23 Definitions. One-page visual illustration.
Euclid's Elements Book. Index

Perpendicular Bisector Index

Perpendicular Bisector.

Kaleidoscope Index

Kaleidoscope Index.

Reflection Index

Reflection, Theorems and Problems.


Euclid's Elements Book I, Proposition 4: (Side-Angle-Side SAS)

iPad Geoboard: Pythagorean Theorem proof by Leonardo 

Geoboard for iPad Pythagorean Theorem Proof by Leonardo.

iPad Geoboard: Pythagorean Theorem proof 

Geoboard for iPad Pythagorean Theorem Proof, Squares (Problem 540).

iPadd Apps Geoboard, triangle with two squares

Geoboard for iPad Gallery: Triangle with two squares (Problem 496).

Semiperimeter and excircles of a triangle.


Semiperimeter and incircle of a triangle.

Semiperimeter, incircle and excircles of a triangle.


Parallelogram with Squares theorem Thébault's Theorem.

Johnson: Intersecting circles

Johnson's Theorem, Intersecting circles.
HTML5 Animation

Varignon and Wittenbauer parallelograms. Quadrilateral: midpoints and trisection points of the edges.


Van Aubel

Van Aubel's Theorem. Quadrilateral with Squares. Proof with animation.

Langley's Problem Adventitious angles. 20° isosceles triangle with animation.

Geometry problem 1329

Geometry Problem 1329.
Two Squares Side by Side, Parallel, Perpendicular, 90 Degrees, Congruence.

Geometry problem 1328

Geometry Problem 1328.
Two Squares Side by Side, Perpendicular, 90 Degrees, Congruence.

Geometry problem 1317

Geometry Problem 1317.
Triangle, Excircle, Chord, Tangent, Midpoint, Arc, Sum of two Segments, Congruence.

Geometry problem 1316

Geometry Problem 1316.
Triangle, Incircle, Tangent, Chord, Midpoint, Sum of two Segments, Congruence.

Geometry problem 1315

Geometry Problem 1315.
Triangle, Incircle, Tangent, Chord, Circle, Congruence.

Geometry problem 1314

Geometry Problem 1314.
Equilateral Triangle, Incircle, Inscribed Circle, Tangent, Congruence.

Geometry problem 1313

Geometry Problem 1313.
Regular Decagon, Pentadecagon, Equilateral Triangle, Congruence.

Geometry problem 1304

Geometry Problem 1304.
Triangle, 120 Degrees, Angle Bisector, Measurement.

Geometry problem 1303

Geometry Problem 1303.
Triangle, 60 Degrees, Angle Bisector, Measurement.

Geometry problem 1302

Geometry Problem 1302.
Triangle, Median, Midpoint, Circles, Diameters, Congruence.

Geometry problem 1295

Geometry Problem 1295.
Right Triangle, Incenter, Incircle, Excenter, Excircle, Congruence, Angle.

Geometry problem 1293

Geometry Problem 1293.
Triangle, Altitudes, Two Squares, Center, Concurrent Lines, Midpoint.

Geometry problem 1291

Geometry Problem 1291.
Three Squares, Collinear Vertices, Midpoint, Congruence.

Geometry problem 1287

Geometry Problem 1287.
Triangle, 40-100-40 Degrees, Congruence, Area, Metric Relations, Measurement.

Geometry problem 1286

Geometry Problem 1286.
Triangle, Quadrilateral, 60, 135, 105 Degree Angles, Congruence, Measurement.

Geometry problem 1285

Geometry Problem 1285.
Triangle, Quadrilateral, 60, 150, 90 Degree Angles, Congruence, Measurement.

Geometry problem 1284

Geometry Problem 1284.
Two Equilateral Triangle, Midpoint, Congruence.

Geometry problem 1278

Geometry Problem 1278.
Square, 3-4-5 Right Triangle, Midpoint.

Geometry problem 1272

Geometry Problem 1272.
Isosceles Triangle, Median, Midpoint, Perpendicular, 90 Degrees, Angles, Congruence.

Geometry problem 1250

Geometry Problem 1250.
Cyclic or Inscribed Quadrilateral, Circle, Diameter, Congruence.

Geometry problem 1238

Geometry Problem 1238
Square, Equilateral Triangle, Metric Relations. Mobile Apps.

Geometry problem 1237

Geometry Problem 1237
IMO 2016, Problem 1, Triangle, Congruence, Parallel Lines, Midpoint, Concurrency.

Geometry problem 1234

Geometry Problem 1234
Quadrilateral, 60 Degrees, Midpoint, Congruence, Cyclic Quadrilateral, Concyclic Points.

Geometry problem 1230

Geometry Problem 1230
Quadrilateral, 60 Degrees, Congruence, Metric Relations.

Geometry problem 1226

Geometry Problem 1226
Quadrilateral, Squares, Centers, Midpoints, Congruence.

Geometry problem 1225

Geometry Problem 1225
Equilateral Triangle, Circumcircle, Angle Bisector, Congruence.

Geometry problem 1222

Geometry Problem 1222
Doubling the Cube, Triangle, 90, 120 degrees, Perpendicular, Congruence.

Geometry problem 1220

Geometry Problem 1220
Equilateral Triangles, Midpoints, 60 Degrees, Congruence.

Geometry problem 1219

Geometry Problem 1219
Equilateral Triangles, Midpoints, 60 Degrees, Congruence, Rhombus.

Geometry problem 1218

Geometry Problem 1218
Scalene Triangle, Equilateral Triangles, Midpoints, 60 Degrees, Congruence.

Geometry problem 1213

Geometry Problem 1213
Triangle, Circumcircle, Altitudes, Cyclic Quadrilateral, Congruence.

Geometry problem 1209

Geometry Problem 1209
Triangle, Circle, Excircle, Excenter, Circumcircle, Congruence.

Geometry problem 1207

Geometry Problem 1207
Triangle, Circle, Incenter, Circumcenter, Excenter, Circumradius, Perpendicular, 90 Degrees.

Geometry problem 1206

Geometry Problem 1206
Circle, Angle Bisector, Secant, Triangle, Circumcircle, Congruence, Area.

Geometry problem 1203

Geometry Problem 1203
Right Triangle, Square, Angle Bisector, Three Congruent Quadrilaterals.

Geometry problem 1202

Geometry Problem 1202
Four Squares, Two Equal Parallelograms, Congruence.

Geometry problem 1195

Geometry Problem 1195
Square, Two Rectangles, Congruence, Metric Relations.

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HomeGeometry | Congruence | Email | by Antonio Gutierrez
Last updated: Apr 10, 2017