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

Nazi Germany, Nazi SS troops marching with victory standards at the Party Day rally in Nuremberg, Germany, 1933. (Schutzstaffel, Nazi Party, Nurnberg)

Why Was Nazi Germany Called the Third Reich?

Ahura Mazda - relief of the Zoroastrian god Ahura Mazda at the ancient ruins of Persepolis in Iran. Also known as Ormazd Zoroastrianism,

Which Religion Is the Oldest?

Battle of the Alamo from "Texas: An Epitome of Texas History from the Filibustering and Revolutionary Eras to the Independence of the Republic, 1897. Texas Revolution, Texas revolt, Texas independence, Texas history.

6 Wars of Independence

Titanic infographic. The 30th anniversary of its discovery is September 1, 2015. SPOTLIGHT VERSION.

Timeline of the Titanic’s Final Hours

Hemp (Cannabis sativa).

9 Mind-Altering Plants

Shot of a woman drinking a glass of water at home. Drink sip hydration

How Much Water Should a Person Drink in a Day?

All Saints Day. All Souls Day. Candles in cemetery in Poland on All Saints Day, November 1. All Souls Day, November 2. Christian church, All Hallows, Solemnity of All Saints, Feast of All Saints, purgatory, Roman Catholic church

7 Unique Burial Rituals Across the World

triangle: Related Content

Written and fact-checked by 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 →

Topics

Pascal’s triangle Heron’s formula spherical triangle right triangle trigonometry Bridge of Asses triangle inequality Ceva’s theorem Menelaus’ theorem angle hexagon

Key People

Heron of Alexandria

Greek mathematician