Online Geometry: Congruence, Rotation, Translation, Reflection - Page 1
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Euclid's Elements
Book I, 23 Definitions. One-page visual illustration.
Euclid's Elements Book.
Index |
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Perpendicular
Bisector. |
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Kaleidoscope Index.
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Reflection, Theorems and
Problems. |
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Euclid's Elements Book I, Proposition 4: (Side-Angle-Side SAS) |
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Geoboard
for iPad Pythagorean Theorem Proof by Leonardo. |
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Geoboard
for iPad Pythagorean Theorem Proof, Squares (Problem 540). |
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Geoboard
for iPad Gallery: Triangle with two squares (Problem 496). |
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Semiperimeter and excircles of a triangle.
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Semiperimeter and incircle of a triangle. |
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Semiperimeter, incircle and excircles of a triangle.
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Parallelogram with Squares theorem Thébault's Theorem.
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Johnson's Theorem,
Intersecting circles.
HTML5 Animation |
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Varignon and Wittenbauer parallelograms. Quadrilateral: midpoints and
trisection points of the edges.
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Van Aubel's Theorem.
Quadrilateral with Squares. Proof with animation.
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Langley's Problem
Adventitious angles. 20° isosceles triangle with animation.
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Geometry Problem 1559:
Proving BC Bisects Segment DE. This geometry problem challenges students at high school and college levels. |
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Geometry Problem 1558:
The midpoints of segments connecting corresponding vertices of equilateral triangles form an equilateral triangle. |
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Geometry Problem 1557:
Calculate the Angle DHG in Right Triangle ABC. The problem involves: equilateral,
isosceles, midpoint and congruence |
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Geometry Problem 1556: Right Triangle ABC and Inscribed Circle. The problem involves circle, chords, tangent, perpendicular lines, and congruence |
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Geometry Problem 1554: Finding the Length of Side AB in Triangle ABC |
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Geometry Problem 1553: Solving for OC in Triangle ABC with Unique Angle Bisectors |
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Geometry Problem 1550: Solving for Segment BD: An Angle Puzzle in Right Triangle ABC: A High School Level Investigation |
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Geometry Problem 1538: Unlocking the Secrets of Triangular Geometry: Solve for the Area of a Quadrilateral Using External Squares and a Segment Length. |
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Geometry
Problem 1529: Unlock the Mystery of Triangles: Solving for the Missing Angle with 100-50-30 Degree Angles and Cevian Lengths - A High School Challenge.
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Geometry
Problem 1526: Mastering Geometry Problem-Solving: Discover the Distance Between Two Sides in a Parallelogram Using Bisectors and Distance Measures.
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Geometry
Problem 1525 and a Thematic Poem.
Unveiling the Secrets of an Equilateral Triangle in Right Triangle Geometry: Finding the Midpoint Distance between Segments. |
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Geometry
Problem 1524 and a Thematic Poem.
Unlock the Mystery of Parallelograms: Discover the Length of Segment between the Intersecting Angle Bisectors. |
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Geometry
Problem 1523 and a Thematic Poem.
Discover How to Calculate the Length of the Altitude in an Isosceles Triangle - Get Expert Geometry Tips Now!
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Geometry
Problem 1513 and a Thematic Poem.
Solving the base in a Right Trapezoid with Double Angle and Sum of Two
Sides. Difficulty Level: High School. |
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Geometry
Problem 1511 and Poem.
Finding the Altitude of an Isosceles Triangle Using Distances from a Point on the Extension of the Base. Difficulty Level: High School. |
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Geometry
Problem 1510 and Poem.
Congruence of Triangles, Perimeter, Measurement. Difficulty Level: High School. |
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Geometry
Problem 1509 and Poem.
Congruence of Triangles in a Trapezoid and a Square, Measurement. Difficulty Level: High School. |
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Geometry
Problem 1503.
Triangle, Incircle, Tangent, Congruence, Perpendicular. |
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Geometry
Problem 1501.
Square, Exterior Point, Congruent Angles, Segment, Measurement. |
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Geometry
Problem 1499.
Triangle, Angles, Cevian, Congruence, Isosceles, Equilateral, Auxiliary Construction. |
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Geometry
Problem 1496.
Triangle, Congruence, Isosceles, Double Angle, 30 Degrees. |
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Geometry Problem 1461.
Quadrilateral, Triangle, Angles, 30-60 Degree, Congruence, Auxiliary Lines. |
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Dynamic Geometry Problem 1447.
Outer Vecten Point. Step-by-step
illustration using GeoGebra. |
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Dynamic Geometry Problem 1445.
Van Aubel's theorem, Quadrilateral and Four Squares, Centers. Step-by-step animation using GeoGebra. |
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Geometry Problem 1431.
Triangle, Circumcircle, Parallel Chord, Apollonius, LLC, Congruent Angles, Poster, Conformal Mapping. |
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Geometry Problem 1429. Triangle, Median, 15-30 degree, Angle, Congruence. |
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Geometry Problem 1428. Intersecting Circles, Tangent Line, Triangle, Square, Area. |
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Geometry Problem 1406. Four Congruent Circles, Measurement, Metric Relations,
Sum of the Squares. |
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Geometry Problem 1405. Four Congruent Circles, Congruent Chords. |
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Geometry Problem 1404. Three Circles, Center, Intersecting Points, Collinearity, Congruence. |
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Geometry Problem 1403. Quadrilateral, 90 Degree Angle, Perpendicular, Congruence. |
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Geometry Problem 1401. Right Triangle with three circles on the sides, Isosceles, Diameter, Center, Tangent, Congruence. |
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Geometry Problem 1389. Triangle, 40-120-20 degree, Angle, Congruence. |
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Geometry Problem 1388. Triangle 40-60-80 degree, Incenter, Congruence. |
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Geometry Problem 1382. Circle, Diameter, Radius, Perpendicular, Congruence. |
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Geometry Problem 1380. Common
Internal Tangents. Circles, Secant, Congruent Chords. |
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Geometry Problem 1379. Common External Tangents. Circles, Secant, Congruent Chords. |
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Geometry Problem 1361.
Triangle, Two Nine-Point Circles, Feuerbach's Circle, Euler's Circle, Congruent Angles, Sketch, iPad Apps. |
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Geometry Problem 1359.
Triangle, Circumcircle, Congruent Angles, Midpoints. |
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Geometry Problem 1356.
Quadrilateral, Triangle, Angle, 30 Degrees, Congruence. |
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Geometry Problem 1353. Tangent Circles, Perpendicular Diameters, Congruence, 30 Degrees. |
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Geometry Problem 1349. Three Squares, 90 Degrees, Perpendicular Lines, Diagonal. Math Infographic. |
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Geometry Problem 1348. Three Concentric Circles, Equilateral Triangle, Perpendicular Bisector, Congruence. |
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Geometry Problem 1347. Triangle, Angle Bisector, Congruence, Circumcircle, Tangent, Equilateral Triangle. |
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Geometry Problem 1329.
Two Squares Side by Side, Parallel, Perpendicular, 90 Degrees, Congruence. |
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Geometry Problem 1328.
Two Squares Side by Side, Perpendicular, 90 Degrees, Congruence. |
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Geometry Problem 1317.
Triangle, Excircle, Chord, Tangent, Midpoint, Arc, Sum of two Segments, Congruence. |
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Geometry Problem 1316.
Triangle, Incircle, Tangent, Chord, Midpoint, Sum of two Segments, Congruence. |
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Geometry Problem 1315.
Triangle, Incircle, Tangent, Chord, Circle, Congruence. |
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Geometry Problem 1314.
Equilateral Triangle, Incircle, Inscribed Circle, Tangent, Congruence. |
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Geometry Problem 1313.
Regular Decagon, Pentadecagon, Equilateral Triangle, Congruence. |
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Geometry Problem 1304.
Triangle, 120 Degrees, Angle Bisector, Measurement. |
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Geometry Problem 1303.
Triangle, 60 Degrees, Angle Bisector, Measurement. |
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Geometry Problem 1302.
Triangle, Median, Midpoint, Circles, Diameters, Congruence. |
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Geometry Problem 1295.
Right Triangle, Incenter, Incircle, Excenter, Excircle, Congruence, Angle. |
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Geometry Problem 1293.
Triangle, Altitudes, Two Squares, Center, Concurrent Lines, Midpoint. |
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Geometry Problem 1291.
Three Squares, Collinear Vertices, Midpoint, Congruence. |
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Geometry Problem 1287.
Triangle, 40-100-40 Degrees, Congruence, Area, Metric Relations, Measurement. |
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Geometry Problem 1286.
Triangle, Quadrilateral, 60, 135, 105 Degree Angles, Congruence, Measurement. |
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Geometry Problem 1285.
Triangle, Quadrilateral, 60, 150, 90 Degree Angles, Congruence, Measurement. |
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Geometry Problem 1284.
Two Equilateral Triangle, Midpoint, Congruence. |
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Geometry Problem 1278.
Square, 3-4-5 Right Triangle, Midpoint. |
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Geometry Problem 1272.
Isosceles Triangle, Median, Midpoint, Perpendicular, 90 Degrees, Angles, Congruence. |
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Geometry Problem 1250.
Cyclic or Inscribed Quadrilateral, Circle, Diameter, Congruence. |
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Geometry Problem 1238
Square, Equilateral Triangle, Metric Relations. Mobile Apps. |
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Geometry Problem 1237
IMO 2016, Problem 1, Triangle, Congruence, Parallel Lines, Midpoint, Concurrency. |
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