College Geometry Online, eLearning


Online Geometry: Rectangle, Theorems and Problems

Rectangle Index


Euclid Elements Book X, Lemma for Proposition 33

Euclid's Elements, Book X, Lemma for Proposition 33 One page visual illustration.

Eyeball Theorem: Animated Angle to Geometry Study.
Chords and Rectangle.

Eight Point Circle Theorem. Elearning

Eight-Point Circle Theorem
Step-by-Step construction, Manipulation, and animation.

Mindpoints and Rectangle

Sangaku Problem. The incenters of four triangles in a cyclic quadrilateral form a rectangle.

Cyclic Quadrilateral: Ratio of the Diagonals
The ratio of the diagonals of any cyclic quadrilateral equals the ratio of the sums of the rectangles contained by the sides that share the diagonals' end points 

Area of a square

Area of a Square Index.

Interactive Mind Map of the Van Hiele Model of Geometric Thought
Level 2. Abstraction: learners recognize relationships between types of shapes. They recognize that all squares are rectangles, but not all rectangles are squares.  

Triangle and Squares 22
Rectangles of equal area. 

Triangle and Squares 20
Rectangles of equal area. 

Parallelograms Index

Parallelograms Index.

Billiards and Geometry Index

Billiards and Geometry - Index
Billiards Table

Hippocrates and Squaring the Circle

Thébault's Theorem. Parallelogram with Squares theorem

Euclid's Elements 23 definitions

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

Geometry Problem 1552

Geometry Problem 1552: Exploring Angle C in Triangle ABC with Given Angle A and Side Lengths

Geometry Problem 1530

Geometry Problem 1530: Unlock the Secrets of Geometric Angles: Calculate the Measurement of an Angle in a Square and Rectangle Figure Today! - A High School Challenge.

Geometry Problem 1523

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! .

Geometry Problem 1520

Geometry Problem 1520 and a Thematic Poem.
Discovering Distances in a Rectangle with an Exterior Point: A Geometry Challenge.

Dynamic Geometry 1472

Dynamic Geometry 1472.
Cyclic Quadrilateral, Perpendicular Diagonals, Rectangle, Step-by-step Illustration.

Dynamic Geometry 1452

Dynamic Geometry 1452.
Japanese Theorem, Sangaku, Cyclic Quadrilateral, Incenter, Rectangle, Inradius. Step-by-step illustration using GeoGebra.

Problem 1439

Geometry Problem 1439.
Rectangle, Diagonal, Perpendicular, Circles, Areas, Art, Poster, Typography, iPad Apps.

Problem 1400

Geometry Problem 1400.
Triangle with three rectangles on the sides, Perpendicular Bisectors, Concurrency.

Problem 1396

Geometry Problem 1396.
Triangle with three rectangles on the sides, Vertices, Perpendicular lines, Concurrency.

Problem 1395

Geometry Problem 1395.
Triangle with three rectangles on the sides, Midpoints, Perpendicular lines, Concurrency.

Geometry problem 1352

Geometry Problem 1352.
Rectangles, Sum of Squared Distances.

Geometry problem 1318

Geometry Problem 1318.
Rectangle, Equilateral Triangle, Distances, Perpendicular, Measurement.

Geometry problem 1198

Geometry Problem 1198
Right Triangle, Square, Rectangle, Quadrilateral, Altitude, Equal Areas.

Geometry problem 1195

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

Geometry problem 1185

Geometry Problem 1185
Similar Rectangles, Four Quadrilaterals, Sum of the Areas, Metric Relations.

Geometry problem 1144

Geometry Problem 1144.
Three Equal Squares, Diagonals, Perpendicular, 90 Degrees, Angle Bisector.

Geometry Problem 1070

Geometry Problem 1070.
Circle, Chord, Equilateral Triangle, Square, Rectangle, Area, Diameter, Perpendicular.

Geometry Problem 1046

Geometry Problem 1046.
Rectangle, Circle, Circumradius, Metric Relations.

Geometry Problem 989

Geometry Problem 989.
Arbelos, Semicircles, Diameter, Perpendicular, 90 Degree, Common External Tangent, Rectangle, Midpoint of Arc.

Geometry Problem 971

Geometry Problem 971.
Equilateral Triangle, Rectangle, Common Vertex, Sum of Right Triangles Areas.

Geometry Problem 969

Geometry Problem 969.
Equilateral Triangle, Rectangle, Common Vertex, Right Triangles Areas.

Geometry Problem 968

Geometry Problem 968.
Equilateral Triangle, Rectangle, Common Vertex, Midpoint.

Geometry problem 868, Cyclic Quadrilateral, Circle, Five Rectangles, Four Centers, Congruence

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

Rectangle, Midpoint, Concyclic points

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

Geometry problem 866, Cyclic Quadrilateral, Circle, Rectangle, Center, Congruence, 90 Degrees

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

Three Rectangles, Centers, Angles

Geometry Problem 620
Three Rectangles, Diagonals, Centers, Angles.

Cyclic quadrilateral, Incenter, Excenter

Geometry Problem 601
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Cyclic Quadrilateral, Incenter, Excenter, Rectangle.

Pentagon, Rectangle

Problem 563.
Regular Pentagon, Center, Rectangle, Diagonals, Angle.

Rectangle, Midpoint, Diagonal, Angle Bisector

Problem 537.
Rectangle, Midpoints, Diagonal, Angle Bisector.

Rectangle, Isosceles Right Triangle, Square, Area

Proposed Problem 252.
Rectangle, isosceles right triangle, square, areas.

Proposed Problem 35.
Rectangle, Incenters and Inradii in Cyclic Quadrilateral.

Golden Rectangles Index

Golden Rectangles Index.

Polygon Classification

Polygon Classification. Interactive Mind Map.

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Last updated: Sep 9, 2023