Online Geometry: Recent Additions, Theorems and Problems

Geometry Theorems and Problems - Recent Additions (Page 1 of 15)

Geometry Problem 726.
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Isosceles Triangle, Perpendicular, Midpoint, 90 Degrees.

Geometry Problem 725.
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Kurschak's Dodecagon, Square, Equilateral Triangle, Midpoints, 30, 60 Degrees.

Geometry Problem 724.
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Circumscribed Quadrilateral, Circle, Angle, Incenter, Half the Measure.

Geometry Problem 723.
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Squares, Circumscribed Circles, Collinear points.

Geometry Problem 722.
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Squares, Circumscribed Circles, Collinear points.

Geometry Problem 721.
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Triangle, Orthocenter, Circumcircle, Altitude, Collinear points.

Geometry Problem 720.
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Excenter, Intersecting Circles, Angle, Measurement.

Geometry Problem 719.
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Incenter, Intersecting Circles, Angle, Measurement.

Geometry Problem 718.
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Intersecting Circles, Midpoint, Angle, Measurement.

Geometry Problem 717.
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Intersecting Circles, Midpoint, Angle, Measurement.

Geometry Problem 716.
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Problem 716. Intersecting Circles, Center, Radius, Perpendicular, 90 Degrees.

Geometry Problem 715.
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Triangle, Altitudes, Parallel, Circumcircle, Angle, Measurement.

Geometry Problem 714.
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Triangle, Parallel, Cevians, Midpoints, Median, Ceva Theorem.

Geometry Problem 713.
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Tangent Circles, Diameter, Chord, Tangent, Incenter, Incircle, Triangle.

Geometry Problem 712.
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Semicircle, Diameter, Tangent, Perpendicular, Angle Measure.

Geometry Problem 711.
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Rectangle, Midpoint, Angle, Concyclic Points, Cyclic Quadrilateral.

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

Problem Solving Techniques, Interactive Mind Map.

Geometry Problem 709.
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Parallelogram, Midpoint, Diagonal, Metric Relations, Triangle.

Geometry Problem 708.
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Circle, Tangent, Intersecting, Lune, Area, Diameter.

Geometry Problem 707.
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Triangle, Excenters, Excircles, Angle Bisectors, Angle, Measurement.

Geometry Problem 706.
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Triangle, Cevian, Three Circumcenters, Circumcircles, Concyclic Points, Cyclic quadrilateral.

Geometry Problem 705.
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Intersecting Circles, Diameter, Angles, Measurement.

Geometry Problem 704.
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Triangle, Orthocenter, Altitude, Midpoint, Perpendicular.

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

Geometry Problem 702.
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Triangle, Circumcircle, Parallel, Concyclic Points.

Geometry Problem 701.
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Intersecting Circles, Diameter, Perpendicular, Angles, Congruence.

Concyclic Points.
 

Geometry Problem 700.
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Equilateral Triangle, Circle, Circular Segment, Midpoint of a side, Metric Relations.

Geometry Problem 699.
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Equilateral Triangle, Circle, Circular Segment, Midpoint, Metric Relations.

Circular Segment. Index.
Theorems and Problems. 

Geometry Problem 698.
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Quadrilateral, Diagonal, Angle Bisector, Triangle, 120 Degrees.

Geometry Problems 691 - 700.
Triangle, Quadrilateral, Circle, Metric Relations, Square, 30-60-120 Degrees, Area, Congruence.

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

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

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

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

Geometry Problem 693.
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Square, Inscribed and Circumscribed Circle, Areas, Mind Map, Polya.

Geometry Problem 692.
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Quatrefoil, Four Equal Circles and a Circle Inscribed in a Square, Areas, Mind Map, Polya.

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

Problem 690: Distance between the Incenter and the Centroid of a Triangle.
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Formula in terms of the sides a,b,c.

Geometry Problems 681 - 690.
Triangle, Circle, 60 Degrees, Incenter, Circumcenter, Orthocenter, Parallelogram, Metric Relations, Congruence, Similarity.

Geometry Problem 689.
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Triangle, Three Excircles, Tangency points, Tangent lines, Concurrent Lines, Mind Map.

Geometry Problem 688.
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Triangle, Angles, 10, 20, 30, 40, 60 Degrees, Measure, Mind Map, Polya.

Area of a Parallelogram.
Theorems and Problems Index.

Geometry Problem 687.
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Triangle, Three Excircles, Tangency points, Concurrent Lines.

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

Geometry Problem 685
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Isosceles Triangle, 100-40-40 Degrees, Angles, Congruence.

Geometry Problem 684: Outer Nagel Point.
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Triangle, Excircles, Incircle Tangency points, Concurrent lines, Semi-perimeter, Ceva theorem.

Geometry Problem 683: Nagel Point.
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Triangle, Excircles, Tangency points, Concurrent lines, Semi-perimeter, Ceva theorem.

Geometry Problem 682: Gergonne External Point.
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Triangle, Excircle, Tangency points, Concurrent lines, Semiperimeter, Ceva theorem.

Geometry Problem 681: Gergonne Point.
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Triangle, Incircle, Tangency points, Concurrent lines, Semiperimeter, Ceva theorem.

Geometry Problem 680.
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Concentric Circles, Radii, Chords, Perpendicular, Metric Relations.

100 Geometry Problems Collection

Geometry Problem 679.
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Triangle, Circle, Median, Proportion.

Geometry Problem 678.
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Triangle, Simson Line, Circumcircle, Tangent, Parallel, Perpendicular, Collinear Points.

Geometry Problem 677.
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Parallelogram, Midpoint, Diagonal, Metric Relations.

Geometry Problem 676.
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Circles, Diameter, Tangent, Chord, Metric Relations.

Geometry Problem 675.
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Intersecting Circles, Secant, 45 and 90 Degrees, Collinear Points.

Geometry Problem 674.
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Triangle, Altitude, Angles.

Geometry Problem 673.
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Internally tangent circles, Chord, Tangent, Metric Relations.

Geometry Problem 672.
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Internally tangent circles, Chord, Tangent, Geometric Mean.

Geometry Problem 671.
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Triangle, Cevian, Angles, Congruence.

Geometry Problem 670.
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Triangle, 60 Degrees, Orthocenter, Incenter, Circumcenter, Congruence.

Geometry Problem 669.
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Triangle, Circumcircle, Incenter, Midpoint, Collinear points, Mind Map.

Geometry Problem 668.
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Right triangle, Incircles, Parallel, Common Tangent, Mind Map.

Geometry Problem 667.
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Intersecting Circles, Secant, Tangent, Metric Relations, Mind Map.

Geometry Problem 666.
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Intersecting Circles, Secant, Tangent, Concyclic points, Mind Map.

Geometry Problem 665.
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Intersecting Circles, Secant, Tangent, Angles, Mind Map.

Geometry Problem 664.
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Triangle, 60 Degrees, Orthocenter, Incenter, Circumcenter, Angles, Triangle centers.

Geometry Problem 663.
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Scalene Triangle, 60 Degrees, Altitude, Angle Bisector, Perpendicular Bisector, Concurrent lines.

Video solution: Problems 1-6 (Spanish version)
By Eder Contreras and Cristian Baeza, Chile.

Geometry Problem 662.
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Triangle, Incenter, Circumcenter, Orthocenter, Circle, Angle, Measurement.

Geometry Problem 661.
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Intersecting Circles, Centers, Secant, Parallelogram.

Geometry Problem 660.
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Triangle, Circle, Diameter, Perpendicular Lines.

Geometry Problem 659.
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Parallelogram, Parallel Lines, Collinear Points.

Geometry Videos Index

Geometry Problem 658.
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Triangle, Altitudes, Diameter, Circle, Angles.

Geometry Definitions.

Geometry Problem 657.
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Triangle, Incircle, Tangency Points, Parallel Lines, Congruence.

Geometry Definitions.

Geometry Problem 656.
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Triangle, Cevian, Concurrent Lines.

Dynamic Geometry Software: GeoGebra 3.2 Help Document
GeoGebra is a dynamic geometry software. Constructions can be made with points, vectors, segments, lines, polygons, conic sections, and functions.
Interactive Mind Map

Geometry Problem 655.
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Archimedes Book of Lemmas: Proposition 15
Circle, Inscribed Regular Pentagon, Radius.

Semicircle. Index.
Theorems and Problems.

Geometry Problem 654.
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Archimedes Book of Lemmas: Proposition 14
Salinon, Semicircles, Diameter, Circle, Area.

Geometry Problem 653.
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Archimedes Book of Lemmas: Proposition 13
Circle, Chord, Perpendicular, Congruence.

Geometry Problem 652.
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Archimedes Book of Lemmas: Proposition 12
Perpendicular chords, Arcs, Radius.

Geometry Problem 651.
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Archimedes Book of Lemmas: Proposition 11
Perpendicular chords, Arcs, Radius.

Geometry Problem 650.
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Tangent Circles, Diameter, Radius, Chord, Perpendicular.

Geometry Problem 649.
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Archimedes Book of Lemmas: Proposition 10
Tangent, Chord, Parallel, Midpoint.

Geometry Problem 648.
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Archimedes Book of Lemmas: Proposition 9
Perpendicular chords, Arcs.

Geometry Problem 647.
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Archimedes Book of Lemmas: Proposition 8
Angle trisection. Neusis construction.

Geometry Problem 646.
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Archimedes Book of Lemmas: Proposition 7
Square,Inscribed and Circumscribed Circles, Area.

Geometry Problem 645.
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Archimedes Book of Lemmas: Proposition 6
Semicircle, Circle, Perpendicular, Arbelos, Inscribed Circle.