Apollonius' Tangency Problem for Three Circles Illustration with animation and sound.

Archimedes' Book of Lemmas:Try to solve the Archimedes' problems of geometry (High school Level)

The Archimedes Palimpsest

Archimedes: 3.14159 is Close Enough

Archimedes Index

Blanchet Theorem

Brahmagupta's Theorem Cyclic quadrilateral.

Butterfly Theorem Proof. Puzzle.

Butterfly Theorem Introduction.

Carnot's Theorem

Ceva's Theorem Concurrency

Circles

Clifford's Circle Chain Theorems

Einstein and Pythagoras theorem proof

Equilic Quadrilateral Five theorems.

Equal Incircles Theorem. Interactive presentation.

Eyeball Theorem

Fagnano's Problem

Feuerbach Theorem

Feuerbach Point, Acute Triangle illustration

Geometry, table of contents

Gergonne Point Theorem

De Gua's Theorem

Johnson Theorem

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

Kurschak's Tile and Theorem

Langley Theorem. Adventitious angles.

Lemoine Theorem

Lunes of Hippocrates 1, 2 , 3, 4

Mascheroni Construction with compass alone. Midpoint of a segment.

Menelaus' Theorem. Triangle and transversal line.

Miquel's Pentagram Theorem Proof

Miquel's Pentagram Dynamic Geometry

Monge & d'Alembert Three Circles Theorem I Dynamic Geometry

Monge & d'Alembert Three Circles Theorem II Dynamic Geometry

Morley's Theorem

Nagel Point Theorem Proof

Napoleon's Theorem

Newton's Theorem

Nine-Point Center, Nine-Point Circle, Euler Line

Parallelogram&Squares

Pascal's Mystic Hexagram Theorem Proof

Pentagons and Pentagrams. Menelaus and Collinearity.

Platonic Solids Interactive animation

Poncelet's Theorem

Proposed Problems about congruence of line segments, angles, and triangles.
Key Theorems or Facts to know

Proposed Problem 29, Geometry Help: Facts you should know

Proposed Problem 39.

Proposed Problem 39 Geometry Help.

Ptolemy's Theorem.

Pythagoras Right Triangles, Formulas and Facts

Pythagoras and Circle Area

Cyclic Quadrilateral: Ratio of the Diagonals 

Quadrilaterals Table of Content

Sangaku Problem 1

Sangaku Problem 2

Sangaku Problem 3

Sangaku Problem 41. "Mickey Mouse."

Sawayama -Thebault's theorem

Semiperimeter and Incircle

Semiperimeter and Excircles

Semiperimeter, Incircle and Excircles

Seven Circles Theorem

Simson Line

Simson Line: Angle

Steiner's Theorem

100° Isosceles

Triangles

Triangles and Lissajous Art

Triangle with the bisectors of the exterior angles. Collinearity.

Triangle and Squares. 19 theorems, visual illustrations.

Triangle and Squares 18 Sangaku Problem

Triangle and Squares 19

Triangle&Squares 0 Two squares

Triangle&Squares 1 Two squares

Triangle&Squares 2 Two squares

Triangle&Squares 3 Three squares

Triangle with Squares 4 Finsler-Hadwiger Theorem

Triangle with Squares 5: Median and Altitude

Triangle with Squares 6: Four squares

Triangle Centers

Van Aubel's Theorem

Adjacent Angles

Varignon & Wittenbauer

 Triangle Centers

 Inspiration for Problem Solving

  The Landscape of Terms

 The election of the New Seven Wonders of the World

 M.C. Escher and Geometric Art

 Vincent Van Gogh and Geometric Art

 Home

Cuzco Ancient Inca Empire Capital.

Inca History according to Guaman Poma's work in 1615.

Inca Calendar

The Thirteen Towers of Chankillo, Peru.
Stone Towers Are Decoded as Earliest Solar Observatory in the Americas.

Cuzco City Map

Cuzco Panorama View

Cuzco Sacsayhuaman Fortress. Panorama View.

Cuzco Chinchero Panorama View

Machu Picchu Lost City of the Incas.

Machu Picchu and Geometric Art

Machu Picchu and the Flower of Life

Machu Picchu Map Interactive with zoom.

Machu Picchu and Sierpinski Triangle.

Machu Picchu Condor's Eye View

Machu Picchu and the Bridge

Machu Picchu and the 21 finalist for the New Seven Wonders of the World

Machu Picchu, interactive panorama view from San Miguel Mountain.

Machu Picchu Trekking View.

Machu Picchu: Top Ten Feats of Man-Made Wonder, Picked by Structural Engineers

Inca Trail to Machu Picchu Panorama View

Inca Trail to Machu Picchu

Inca Trail to Machu Picchu: Huinay Hayna

Lake Titicaca and the Inca Manco Capac

Inca Quipu Data Structure.

Nazca Lines One of humanity's mysteries.

Nazca Lines Animation. Mystery on the Desert.

Nazca Lines: The Monkey. Geometric Art.

Nazca Lines, the Hummingbird. Satellite image and size comparison.

Nazca Lines: "The Needle and Thread"

Nazca Lines: The Condor bird. Puzzle: 40 pieces of birds tessellation.

Nazca Lines: The Spider, Puzzle: 44 pieces in a tri-dove style of piece.

Choquequirao, an ancient Inca site

The Lord of Sipan King Tutankhamen of the Americas

Pre-Inca Sican treasures of Peru's Pomac Forest

The Lord of Sipan and Geometric Art

The Lord of Sipan and Spiderman Gold Necklace

Looted Peru Moche Headdress Recovered in London

Caral: the oldest civilization in the New World  Peru opens Caral ruins to tourists.

Vicunas, Inca Gold of the Incas

The Incas and their Civilization

The Incas and Architecture

The Incas and Civil Engineering

The Incas and Irrigation

The Incas and Domestic Animals.