College Geometry Online, eLearning

Angles 30, 60, 90, 120 Theorems and Problems- Table of Content 2

Angles 30, 60, 120 Index 

Triangle Area, 30 Degrees, Incircle

Geometry Problem 619
Triangle Area, 30 Degrees, Incircle, Incenter, Tangent.

Triangle area, 60 degrees

Geometry Problem 618
Triangle Area, 60 Degrees, Incircle, Incenter, Tangent.

Quadrilateral, 60, 75, 135 degrees

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

Triangle, 120 degrees, angle bisectors

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

Circular sector 60 degrees

Proposed Problem 365.
Circular Sector of 60 degrees, Midpoints, Perpendicular, Congruence.

Triangle and angle bisector of 120 degrees

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

Triangle and angle bisector of 60 degrees

Proposed Problem 302.
Triangle, Angle bisector of 60 degrees.

Equilic Quadrilateral.
60 and 120 degrees 

Triangle, Angles

Proposed Problem 281.
Triangles, Angles, Isosceles, Equilateral.
60 degrees angle.

Square, Circle, 90 Arc

Proposed Problem 276.
Square, 90 degree Arcs, 60 degrees angle, Circle, Radius.

Isoscele triangle 80-80-20

Proposed Problem 274.
Isosceles Triangle, 80-80-20, Angles.
60 degrees angle.

Regular hexagon inscribed in a circle

Proposed Problem 262.
Regular Hexagon inscribed in a circle, sum of distances, 60 degrees angle.

Elearning 260: Problem about equilateral triangle

Proposed Problem 260.
Equilateral Triangle, Incircle, Tangency Points, Vertices, Distances, Squares, 60 degrees angle.

Elearning 259: Equilateral triangle, Incircle

Proposed Problem 259.
Equilateral Triangle, Incircle, Tangency Points, Side, Distances, Squares, 60 degrees angle.

Elearning 258: Equilateral triangle, Incircle

Proposed Problem 258.
Equilateral Triangle, Circumcircle, Point, Vertices, Side, Distances, Squares, 60 degrees angle.

Problem 257: Equilateral triangle, circumcircle

Proposed Problem 257.
Equilateral Triangle, Circumcircle, Point, Vertices, Side, Distances, Squares, 60 degrees angle.

Elearning 256: Equilateral triangle

Proposed Problem 256.
Equilateral Triangle, Circumcircle, Point, Vertices, Distances, 60 degrees angle.

Elearning: Napoleon Theorem III

Proposed Problem 248.
Napoleon's Theorem III. Inner and outer Napoleon triangles, Area, 60 degrees angle.

Napoleon Theorem II

Proposed Problem 247.
Napoleon's Theorem II. Internal Equilateral triangles. Inner Napoleon triangle, 60 degrees angle.

Napoleon Theorem I

Proposed Problem 246.
Napoleon's Theorem I. External Equilateral triangles, 60 degrees angle.

Elearning 245: Parallelogram

Proposed Problem 245. Parallelogram with Equilateral triangles

Elearning 243

Proposed Problem 243. Triangle with Equilateral triangles, Parallelogram.

Elearn 242: Equilateral triangle and parallelogram

Proposed Problem 242. Triangle with Equilateral triangles, Parallelogram, 60 degrees angle.

Equilateral triangle, congruence SAS

Proposed Problem 241. Triangle with Equilateral triangles, Congruence.

Triangle with equilateral triangles

Proposed Problem 240. Triangle with Equilateral triangles, Parallelogram, 60 degrees angle.

Viviani theorem, Equilateral triangle, exterior point

Proposed Problem 222. Viviani's theorem, Equilateral triangle, Exterior point, 60 degrees angle, Distances.  

Viviani's theorem I

Proposed Problem 221. Viviani's theorem, Equilateral triangle, Interior point, Distances, 60 degrees angle.  

Elearn 212: 120 degree triangle, area

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

Elearn 211: 60 degree triangle, area

Proposed Problem 211. 60 Degree Triangle, Equilateral triangles, Areas.

Elearn 210

Proposed Problem 210. Triangle, Angles, Auxiliary Lines, 60 degrees angle.

Problem: Triangle, Altitude, Angles

Proposed Problem 199. Triangle, Quadrilateral, Angles.

Trapezoid and triangle problem

Proposed Problem 185. Trapezoid, Triangles and Angles, 60 degrees angle.

Elearning: Triangle, Angle

Proposed Problem 184. Triangle and Angles, 60 degrees angle.

Overlapping circles, Angle

Proposed Problem 182. Overlapping Circles, Find an angle, 60 degrees angle.

Elearning 132

Proposed Problem 132. Triangle, 60 degrees, Orthocenter, Congruence, Midpoint.

Euclid's Elements Book XIII, Proposition 10

Euclid's Elements, Book XIII, Proposition 10 One page visual illustration, 60 degrees angle.

Video: Geometry of Circles, 1979

Geometry of Circles "Sesame Street" by Philip Glass, 1979, 60 degrees angle.

Proposed Problem 50. Triangle with Equilateral triangles, 60 degrees angle.
Seventeen conclusions.

Proposed Problem 44. Angles and triangles, 60 degrees angle.

Proposed Problem 43. Angles and triangles.

Proposed Problem 42. Angles and triangles, 60 degrees angle.

Morley's Theorem

Animated illustration of the celebrated Morley's angle trisector theorem, 60 degrees angle, equilateral triangle. 

Morley's Triangle & Center: Trisection of angles.

Problem, Angle bisector

Problem 50. Triangle with Equilateral triangles, 60 degrees angle.

Proposed Problem 40.
Triangle, Incenter, Excenter, Angles 80, 40, Distances. Angle bisector,
60 degrees angle.

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