Obtuse Angle Theorems and Problems - Table of Content

Euclid's Elements Book I, 23 Definitions. One-page visual illustration. Definition 11: Obtuse Angle.
Euclid's Elements Book. Index

Obtuse Triangle.

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

Feuerbach Theorem, Obtuse Triangle illustration.
Obtuse angle.

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

Angles: 30, 60, Obtuse angle 120 degrees.

Angles: 45, Obtuse angle 135 degrees.

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

Geometry Problem 1033.
Triangle, Angle Obtuse, Circumcircle, Diameter, Area.

Geometry Problem 923.
Quadrilateral, Quadrangle, Obtuse Angle, Triangle, Diagonal, Inequality, Length.

Proposed Problem 429.
Circumscribed and Inscribed Regular Pentagon, Perpendicular, Measurement, Obtuse angle.

Proposed Problem 423.
Triangle, 30, 40 degree, Angle, Congruence, Obtuse angle.

Proposed Problem 422.
Triangle, 24, 30 degree, Angle, Congruence, Obtuse angle.

Proposed Problem 411.
Triangle, Median, Angles, Obtuse angle.

Proposed Problem 410.
Two Regular Pentagons, Obtuse angle, Angle.

Proposed Problem 405.
Quadrilateral, 60, 75, and 135 degrees, Midpoint, Obtuse angle.

Proposed Problem 395.
Square, 15 Degree, Equilateral triangle, Obtuse angle.

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

Proposed Problem 366.
Scalene triangle, Circumcircle, Angles, 60 Degrees, Equilateral triangle, Obtuse angle.

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

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

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

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

Proposed Problem 199. Triangle, Quadrilateral, Angles, Obtuse angle.

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 . Obtuse angle
Geometry Glossary based on the new New York State mathematics standards initiative.

Problem 1. Obtuse Triangle, median and angles.