Triangles: Theorems and Problems 2

Second Fermat Point: Static diagram.
Second Fermat Point: Dynamic diagram.
Triangle, Equilateral triangles, Concurrent lines, GeoGebra, HTML5 Animation for Tablets (iPad, Nexus)

Triangle with Double Angle, Theorems and Problems, Index
 

Napoleon's theorems and problems, Index.

The Simson Line, Theorems and Problems - Index.

Triangle Geometry in the Real World, New York - Slideshow.

Kosnita's Theorem.
Circumcenters, Concurrent lines.

Routh's Theorem - Index
Triangle, Cevians, Area, Ratio.
 

Marion Walter's Theorem and Related Topics: Index

Routh's Theorem 1.
Triangle, Cevians, Ratio of Areas.

Routh's Theorem 2.
Triangle, Cevians, Ratio of Areas.

Routh's Theorem 3.
Triangle, Cevians, Ratio of Areas.

Routh's Theorem 4.
Triangle, Cevians, Ratio of Areas.

Euclid's Elements Book I, Proposition 7
Given two straight lines constructed on a straight line (from its extremities) and meeting in a point,...

Euclid's Elements Book I, Proposition 8: (Side-Side-Side SSS Congruence)

Euclid's Elements Book I, Proposition 5: (Pons Asinorum) Isosceles triangles

Euclid's Elements Book I, Proposition 6: Converse of I.5

Euclid's Elements Book I, Proposition 4: (Side-Angle-Side SAS)

Euclid's Elements Book I, Proposition 3: Given two unequal straight lines, to cut off from the greater a straight line equal to the less

Euclid's Elements Book I, Proposition 2: To place at a given point (as an extremity) a straight line equal to a given straight line

Euclid's Elements Book I, Proposition 1: On a given finite line to construct an equilateral triangle

Carnot's Theorem in an Acute Triangle.

Carnot's Theorem in an Obtuse Triangle.

Geoboard for iPad Pythagorean Theorem Proof by Leonardo.

Geoboard for iPad Gallery: Triangle with two squares (Problem 496).

Geoboard for iPad Gallery: Six squares with a common vertex.

iPad Apps, Geometry Designer Illustration. Circle of van Lamoen.
Interactive Geometry Software for iPad, iPhone, iPod.