Ask the Chatbot Games & Quizzes History & Society Science & Tech Biographies Animals & Nature Geography & Travel Arts & Culture ProCon Money Videos
triangle
Table of Contents
Introduction References & Edit History Related Topics
Images
Standard lettering of a triangle Area of a triangle Pythagorean theorem Three theorems of congruent triangles Figure 6: Construction for similar triangles (see text). Contrasting triangles in Euclidean, elliptic, and hyperbolic spaces. Fundamental theorem of similarity Chinese and Greek geometric theorems triangle inscribed in a circle Figure 9: If the angles of triangle ABC (representing any triangle) are trisected, then triangle DEF is equilateral.
Discover
Queen Elizabeth II addresses at opening of Parliament. (Date unknown on photo, but may be 1958, the first time the opening of Parliament was filmed.)
All 119 References in “We Didn’t Start the Fire,” Explained
Chinese pictograph, calligraphy tablet of Huang Tingjian, a famous calligrapher in Ancient Song Dynasty. The background of Chinese cultural elements.
The World’s 5 Most Commonly Used Writing Systems
July, 2006, Launch of Space Shuttle Discovery STS-121. See attached for full caption information.
Will Light-Speed Space Travel Ever Be Possible?
The Colosseum, Rome, Italy. Giant amphitheatre built in Rome under the Flavian emperors. (ancient architecture; architectural ruins)
New Seven Wonders of the World
Submerged sperm whale off east Sri Lanka coast, mammal
How Did the Sperm Whale Get Its Name?
NBA Lakers Celtics Finals Kevin Garnett shooting.
10 Great Sports Rivalries
Statue of Nostradamus
Nostradamus and His Prophecies

triangle: Related Content

verifiedCite
While every effort has been made to follow citation style rules, there may be some discrepancies. Please refer to the appropriate style manual or other sources if you have any questions.
Select Citation Style
Share
Share to social media
URL
https://www.britannica.com/facts/triangle-mathematics
Written and fact-checked by
The Information Architects of Encyclopaedia Britannica

The Information Architects maintain a master list of the topics included in the corpus of  Encyclopædia Britannica, and create and manage the relationships between them.
The Information Architects of Encyclopaedia Britannica

Photos

Standard lettering of a triangle
Area of a triangle
Pythagorean theorem
Three theorems of congruent triangles
Figure 6: Construction for similar triangles (see text).
Contrasting triangles in Euclidean, elliptic, and hyperbolic spaces.
Fundamental theorem of similarity
Chinese and Greek geometric theorems
triangle inscribed in a circle
Figure 9: If the angles of triangle ABC (representing any triangle) are trisected, then triangle DEF is equilateral.
See All Images →

Related Topics and References

Topics

Key People

Heron of Alexandria
Greek mathematician