Squares, Theorems and Problems

Online Geometry: Similarity, Ratios, Proportions. Theorems and Problems. Page 3 of 5

Similarity

 

Triangle with the bisectors of the exterior angles

Triangle with the bisectors of the exterior angles. Collinearity. Key concept: Menelaus Theorem.
 

Ptolemy's Theorem.
 

Cyclic Quadrilateral: Ratio of the Diagonals
 

Casey Theorem

Casey's Theorem. Generalized Ptolemy's Theorem.

Pascal's Mystic Hexagram Theorem Proof

Eyeball Theorem: Animated Angle to Geometry Study.

Butterfly Theorem Proof with animation.

Monge & d'Alembert Three Circles Theorem II with Dynamic Geometry. You can alter the geometric construction dynamically in order to test and prove (or disproved) conjectures and gain mathematical insight that is less readily available with static drawings by hand. Requires Java Plug-in 1.3 or higher. Please be patient while the applet loads on your computer.

Monge & d'Alembert Three Circles Theorem I with Dynamic Geometry. You can alter the geometric construction dynamically in order to test and prove (or disproved) conjectures and gain mathematical insight that is less readily available with static drawings by hand. Requires Java Plug-in 1.3 or higher. Please be patient while the applet loads on your computer.

Blanchet Theorem

Lemoine Theorem

Nagel Point Theorem. Proof.
 

Pentagons & Pentagrams. I found, exploring with dynamic geometry software, new facts about pentagons and pentagrams. Key concept: Menelaus Theorem.

Hinged tessellation, Dynamic geometry

Interactive Hinged tessellation. Square tessellation - Dynamic Geometry.
Please be patient while the applet loads on your computer. This Java applet requires Java 1.3 or higher.

Circle area and Pythagoras

Problem 99: Circle Area, General Extension to Pythagoras' Theorem.

Proposed Problem 62: Square Diagonal, Inscribed Circle.

Proposed Problem 40.
Triangle, Incenter, Excenter, Angles 80, 40, Distances.

Proposed Problem 40. Geometry Help.
 

Sangaku Proposed Problem 41. "Mickey Mouse."
Three circles, tangents, radii.

Proposed Problem 63: Heptagon Regular, Side and Diagonals.

Morley's Triangle & Center: with interactive animation and manipulation.

Newton's Theorem: Newton's Line. Circumscribed quadrilateral, midpoints of diagonals, center of the circle inscribed.

Pythagoras curiosity. Online tutoring.

The Pythagorean Curiosity Triangles and squares, fifteen conclusions.

Complete quadrilateral: ortholine, Elearning

Complete Quadrilateral: Ortholine-Steiner Line.
Step-by-Step construction, Manipulation, and animation

Newton's Theorem, Newton-Gauss Line: Complete quadrilateral theorem. Using TracenPoche Dynamic Geometry Software, Online Step-by-Step construction, manipulation, and animation.

Archimedes' Book of Lemmas. Exercise your brain. Archimedes wrote the "Book of Lemmas" more than 2200 years ago. Solve these 15 high school level problems and lift up your geometry skills.
 
Proposition 4, Arbelos,

Archimedes' Book of Lemmas.
Proposition 5,
Arbelos, Archimedean Twins.

Archimedes' Book of Lemmas.
Proposition 6,
Arbelos,

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