Welcome to Geometry Theorems and Problems

Geometry, Machu Picchu

 

Geometry Theorems and Problems - Index

Classical theorems

Geometry problems visual index

Geometry Problems - Visual Index.

Online education degree: Open geometry problems

Open Geometry Problems - Index

Ten Geometry Problems, Visual Index

Ten Geometry Problems, Visual Index

Intersection of a Line with a Circle

Intersection of a Line with a Circle
 

Circle Inscribed in a Square

Circle Inscribed in a Square, Theorems and Problems. Index.

Design Geometry Problems

Geometry Problems Gallery Index
1, 2, 3, 4, 5...

Geometry problems 241-250

Geometry Problems 241 - 250.
Triangle, Quadrilateral, Congruence, Area, Parallelogram, Square, Diagonal, Center, Napoleon, Median, Midpoint.

Geometry Problems 121-130

Geometry Problems 121 - 130.
Triangle, Area, Similarity, Trisection, Hexagon, Star, Incenter, Centroid, Parallel, Proportions, Angle Bisector, Ratio

Geometry Problems 111-120

Geometry Problems 111 - 120.
Orthogonal Circles, Triangle, Square, Area, Incircle, Excircle, Tangent, Incenter

Point, Theorems and Problems, Index

Points, Theorems and Problems - Index.

Angle Index

Angles. Theorems and Problems.

Angle Bisector Index

Angle Bisector. Theorems and Problems.

Obtuse Angle Index

Obtuse Angle. Theorems and Problems.

Angles 30, 60, 120 Index

Angles: 30, 60, 120 degrees.

Angle 45, 90, 135, Theorems and Problems

Angles: 45, 135 degrees.

Parallel Lines Index

Parallel lines.

Perpendicular Lines Index

Perpendicular lines.

Concurrent lines, Index

Concurrent lines.

Transversal Line, Index

Transversal Lines.

Collinear Points Index

Collinear Points.
Theorems and Problems

Midpoint Theorems and Problems Index

Midpoints.
Theorems and Problems

Triangles

Triangles.

Equilateral triangles

Equilateral Triangles.

Isosceles Triangle Index

Isosceles Triangle.

Isosceles triangle 80-20-80

Isosceles Triangle 80-20-80.

Classical Pythagorean Theorem

Right Triangle.

Special right triangle 30 60

Special Right Triangles.

Special Right Triangle 30-60 Index

Special Right Triangle 30-60.

Obtuse Triangle Index

Obtuse Triangle.

Altitude of a triangle

Altitude Index.
Theorems and Problems.

Median of a triangle, Index

Median Index.
Theorems and Problems.

Semiperimeter, Perimeter Index

Semiperimeter, Perimeter Index.
Theorems and Problems.

Heron's Formula.
Key facts and
a purely geometric step-by-step proof.
 

Quadrilateral Index 

Quadrilaterals.

Parallelograms Index

Parallelograms Index.

Squares Index

Square.

Triangles and Squares

Squares and Triangles.

Rectangle Index

Rectangle.

Rhombus, Rhombuses, Rhombi

Rhombus.

Trapezoid Index

Trapezoids.

Trapezoid median, Theorems and Problems, Index

Median of a Trapezoid, Theorems and Problems. Index.

Cyclic Quadrilateral Index

Cyclic Quadrilateral.
 

Tangential or Circumscribed Quadrilateral Index, theorems and problems

Tangential or Circumscribed Quadrilateral
 

Equilic Quadrilateral

Equilic Quadrilateral.
 

Complete quadrilateral

Complete Quadrilateral Index.
 

Polygons Index

Polygons.

Pentagon Index

Pentagons.

Heaxagons

Hexagons.

Heptagon index

Heptagons.

Octagon Index

Octagons.

Nonagon or enneagon

Nonagon or Enneagon.

Circles

Circles.

Circular Sector Index

Circular Sector. Index.
Theorems and Problems. 

Archimedes' Book of Lemmas
 

Lunes of Hippocrates
 

Intersecting Circles Index

Intersecting Circles Index.
Theorems and Problems.

Tangent Circles Index

Tangent Circles Index
 

Concentric circles, Index

Concentric Circles. Index.
Theorems and Problems. 

Macheroni Constructions Index

Mascheroni construction with compass alone. Index

Centers

Triangle Centers.

Centroid of a triangle Index

Centroid /Barycenter. Index.

Circumcenter Index

Circumcenter. Index.

Incenter, Incircle, Index

Incenter. Index.

Excenter, Excircle, Index

Excenter. Index.
Excircle, Exradius.

Orthocenter Index

Orthocenter. Index.

Distance between triangle centers

Distances between Triangle Centers Index.

Napoleon Theorem and Problem Index

Napoleon's theorems and problems, Index.

Congruence

Congruence. Index.

Similarity

Similarity, Ratios, Proportions. Index.

Areas

Areas Index.

Area of a triangle, Index

Area of a Triangle Index.

Area of a square

Area of a Square Index.

Classical Theorems

Classical Theorems.

Solid Geometry

Solid Geometry.

Geometric Mean Index

Geometric Mean.

Online education degree: Geometry problems

Problems.

Complete list of Geometry Problems

Complete List of Go Geometry Problems.
Go Geometry Problems.

Archimedes

Archimedes

Fractal Geometry

Fractal Geometry Index.

Hyperbolic Geometry Index

Hyperbolic Geometry Index.

Euclid's Elements 23 definitions

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

Euclidean Geometry Selections

Euclidean Geometry Selections.

Sacred Geometry Index

Sacred Geometry.

Tessellations

Tessellations.

Kaleidoscope Index

Kaleidoscopes Index.  

Geometry Projects Index

Geometry Projects Brainstorming.

Geometric Art

Geometric Art.

Geometry for Children

Geometry for Children.

Steiner Waldor Education Index

Steiner-Waldorf Education Index.

Saturn and Geometry Index

Saturn and Geometry Index.

Software Index

Software Index.

Solid Geometry

Dynamic Geometry.

Geometry Expressions

Geometry Expressions.

TracenPoche Geometry Applications

TracenPoche Interactive Geometry Software Applications.

Wolfram Mathematica and Geometry

Wolfram Mathematica Software.

Wolfram Demonstrations Project and GoGeometry

Wolfram Demonstrations Project & GoGeometry.
Interact with demonstrations using the free Mathematica Player

WolframAlpha Geometry mind map

Wolfram Alpha Examples, Mathematics, Geometry, Interactive Mind Map.

SAT Math Practice Index

SAT Math Practice,
Index.

Golden Rectangles Index

Golden Rectangles.

Go Geometry Education Index

Go Geometry Education Index

Van Hiele Model Index

Van Hiele Model Index
In mathematics education, the Van Hiele model is a theory that describes how students learn geometry.