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triangle
Introduction References & Edit History Related Topics
Images
A labeled triangle with vertices A, B, and C, sides a, b, and c, and a red line segment h drawn from vertex C perpendicular to side c, representing the height. Diagram of a right triangle with a yellow interior, green outline, green angle θ, red right-angle square, and sides labeled a, b, and c. 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 A triangle is inscribed in a circle, with vertices labeled A, B, and C. The central angle theta is shown at the circle's center, formed by two radii meeting at points A and B, illustrating the relationship between the angle and the chord AB.

triangle: References & Edit History

Article Contributors

Primary Contributors

  • Michael McDonough
    Michael McDonough was a media team intern at Encyclopaedia Britannica. He is expected to graduate in 2023 from Northwestern University.

Other Encyclopedia Britannica Contributors

Article History

Type Description Contributor Date
Modified link of Web site: Mathematics LibreTexts - Triangles. Jun 18, 2026
Add new Web site: IOPscience - Physics World - A triangle that matters (PDF). Jan 16, 2026
Added media. Dec 05, 2025
Add new Web site: OpenStax - Contemporary Mathematics - Triangles. Nov 12, 2025
Add new Web site: Open Washington Pressbooks - Technical Math: Applications for the Environmental Sciences - Some Properties of Triangles. Sep 19, 2025
Add new Web site: Wolfram MathWorld - Triangle. Jul 05, 2025
Add new Web site: Mathematics LibreTexts - Triangles. Jan 30, 2025
Add new Web site: British Columbia/Yukon Open Authoring Platform - Math for Trades: Volume 3 - The Basics of Triangles. Dec 20, 2024
Add new Web site: Khan Academy - Classifying triangles. Nov 04, 2024
Add new Web site: Academia - Concept of Triangle: Example of Mathematical Abstraction Two Different Contexts. Sep 28, 2024
Add new Web site: The University of Hawaiʻi Pressbooks - Mathematics for Elementary Teachers - Triangles and Quadrilaterals. Jul 15, 2024
New article added. Jun 12, 2024
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