Triangles: Theorems and Problems 30




Proposed Problem
127. Centroid and Incenter of a Triangle,
Parallel, Proportions.


Proposed Problem
126. Incenter of Triangle, Angle Bisector, Proportions.


Euclid's Elements Book VI, Proposition 3: Angle Bisector Theorem 

The significance of the Pythagorean theorem by Jacob Bronowski.
Pythagorean Theorem, 47th Proposition of Euclid's
Book I. 

Proposed Problem
125. Area of Triangle, Star,
Trisection of Sides.


Proposed Problem
124. Area of triangle,
Similarity, Trisection of Sides.


Proposed Problem
123. Area of triangle,
Similarity, Trisection of Sides.


Proposed Problem
122. Marion Walter's Theorem.
Area of triangle and Hexagon, Trisection of Sides.


Proposed Problem
121. Similarity and Area
of triangle, Trisection of Sides.


Bottema's Theorem:
Triangle and Squares with Interactive
Geometry Software
StepbyStep construction, Manipulation, and animation. 

Complete Quadrilateral: OrtholineSteiner Line.
StepbyStep construction, Manipulation, and animation 

Proposed Problem
120. Area of triangle,
incenter, excircles,
tangent.


Proposed Problem
119. Area of triangle,
incenter, excircle,
tangent.


Proposed Problem
118. Area of triangle,
incenter, excenter,
tangent.
