Obtuse Triangle Theorems and Problems - Table of Content

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

Euclid's Elements Book II, Proposition 12: Law of Cosines.
Obtuse triangle.

Feuerbach Theorem, Obtuse Triangle illustration.
Obtuse triangle.

The Pythagorean Curiosity Triangles and squares, fifteen conclusions.
Several obtuse triangles.

Proposed Problem 368.
Obtuse Triangle, 120 degrees, Angle bisectors, Perpendicular.

Proposed Problem 364.
Obtuse triangle, Congruence, Circles, Diameter, Curvilinear triangle, Area.

Proposed Problem 322.
Square, Inscribed circle, Tangent, Triangle area.
Obtuse triangle.

Proposed Problem 304.
Triangle, Angle bisector of 120 degrees. Obtuse triangle.

Proposed Problem 212. 120 Degree Triangle, Equilateral triangles, Areas.
Obtuse triangle.

Proposed Problem 199. Triangle, Quadrilateral, Angles.

Proposed Problem 112. Area of square and obtuse triangle.

Problem 47. Obtuse Triangle, median, and angles.

Problem 46. Obtuse Triangle, median, and angles.

Problem 14. Obtuse Triangle, median, and angles.

Geometry Online Glossary . Isosceles triangle
Geometry Glossary based on the new New York State mathematics standards initiative.

Problem 1. Obtuse Triangle, median and angles.