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

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

Perpendicular Bisector.

Kaleidoscope Index.

Congruent Triangles: SAS, SSS, ASA. Demonstrates with animation the various relationships of angles and sides to congruency in triangles.

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

Symmetry (1966). Greatest film, a fantasy of dancing images breaking apart, spinning, and converging. Produced by the University of Washington, the Commission on College Physics, and the Polytechnic Institute of Brooklyn.

Geoboard for iPad Pythagorean Theorem Proof by Leonardo.

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

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's Theorem, Intersecting circles.
HTML5 Animation

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

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

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

Geometry Problem 884: The Pythagorean Curiosity
Right Triangles and squares, fifteen conclusions.

Geometry Problem 882
Triangle, Angle x, 2x, 7x, Cevian, Congruence, Auxiliary Lines.

Geometry Problem 868
Cyclic Quadrilateral, Circle, Five Rectangles, Four Centers, Congruence.

Geometry Problem 867
Isosceles Triangle, Median, Perpendicular, Angle, Congruence.

Geometry Problem 866
Cyclic Quadrilateral, Circle, Rectangle, Center, Congruence, 90 Degrees.

Geometry Problem 860
Triangle, Three Medians, Parallel, Parallelogram, Area, Congruence.

Geometry Problem 859
Isosceles Right Triangle, Angles,18, 45 Degrees, Congruence, Perpendicular bisector.

Geometry Problem 858
Isosceles Right Triangle, Cevian, Ratio 2:1, 45 Degrees, Congruence, Angles, Auxiliary Lines.

Geometry Problem 857
Triangle, Median, Midpoint, Angles, 30, 45 Degrees, Congruence, Auxiliary Lines.

Geometry Problem 845
Triangle, Medians, Centroid, Four Circumcenters, Perpendicular, Congruence, Similarity.

Geometry Problem 844
Triangle, Medians, Centroid, Four Circumcenters, Perpendicular, Congruence, Similarity.

Geometry Problem 843
Triangle, Medians, Centroid, Four Circumcenters, Perpendicular, Parallel, Congruence, Similarity.

Geometry Problem 842
Triangle, Medians, Centroid, Four Circumcenters, Perpendicular, Congruence, Similarity.

Geometry Problem 841
Triangle, Medians, Centroid, Circumcenters, Perpendicular, Congruence, Similarity.

Geometry Problem 832
Quadrilateral, Isosceles triangle, 70-70-40 degrees, Congruence, Auxiliary lines, Equilateral triangle.

Geometry Problem 831
Quadrilateral, Diagonal, Midpoint, Opposite Angles, Congruence, Parallelogram.

Geometry Problem 794
Right Triangle, Altitude, Three Incenters, Circumcircles, Incircle, Congruence.

Geometry Problem 770
Parallelogram, Angle Bisector, Triangle, Circumcenter, Circumcircle, Angle Measurement.

Geometry Problem 769
Triangle, Circumcircle, Circumcenter, Orthocenter, Midpoint of arc, Parallel to chord, Congruence.

Geometry Problem 763
Parallelogram, Diagonal, Parallel, Congruence.

Geometry Problem 762
Parallelogram, Midpoint, Perpendicular, Congruence, Isosceles triangle.

Geometry Problem 759
Equilateral Triangle, Transversal, Trisection of sides, Congruence, Angle.

Geometry Problem 758
Equilateral Triangle, Cevians, Trisection of sides, Congruence, Perpendicular, 90 Degrees.

Geometry Problem 752.
Square, Circle, Tangent, Chord, Angle.

Geometry Problem 745.
Circle, 90 Degrees, Chord, Congruence, Perpendicular, Metric Relations.

Geometry Problem 735.
Triangle, Altitude, Perpendicular, Semiperimeter of the Orthic Triangle, Congruence.

Geometry Problem 734.
Triangle, Isosceles, Median, Parallel, Angle Bisector, Congruence, Midpoint.

Geometry Problem 733.
Triangle, Orthocenter, Altitude, Reflection in a line, Circumcircle, Concurrency.

Geometry Problem 732.
Triangle, Altitude, Orthic Triangle, Orthocenter, Congruence, Parallelogram.

Geometry Problem 728.
Triangle, Altitude, Perpendicular, Circumcircle, Midpoint, Intersecting Circles, Concurrency.

Geometry Problem 727.
Triangle, Isosceles, Congruence, Angles, Measurement.

Geometry Problem 710.
Parallelogram, Midpoint, Diagonal, Collinear Points, Metric Relations, Triangle, Similarity, Congruence.

Geometry Problem 703.
Triangle, Incircle, Tangency point, Diameter, Congruence.

Geometry Problem 697.
Square, Circle, Sector, Segment, Tangent, Inscribed, Congruence, Mind Map, Polya.

Geometry Problem 696.
Triangle, Angles, Auxiliary Construction, Congruence, Mind Map, Polya.

Geometry Problem 695.
Triangle, Angles, Auxiliary Construction, Congruence, Mind Map, Polya.

Geometry Problem 694.
Triangle, Angles, 30 Degrees, Auxiliary Construction, Mind Map, Polya.

Geometry Problem 691.
Isosceles Triangle, 80-80-20 Degrees, Angles, Congruence, Mind Map, Polya.

Geometry Problem 686.
Triangle, Three Excircles, Tangency points, Tangent lines, Semi-perimeter, Congruence.

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