equilateral triangle

noun

plural equilateral triangles
: a triangle in which all three sides are the same length

Examples of equilateral triangle in a Sentence

Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
On spherical surfaces, such as that of Earth, an equilateral triangle can consist of three right angles, for instance. — Manon Bischoff, Scientific American, 23 May 2026 So too an equilateral triangle of bright stars; Procyon in Canis Minor, reddish Betelgeuse in Orion and Sirius in Canis Major. — Jamie Carter, Space.com, 14 Apr. 2026 Fold up sides of each circle to form an equilateral triangle with about 3-inch-long, 1-inch-tall sides, pinching together corners to seal. — Marianne Williams, Southern Living, 25 Feb. 2026 Consider the symmetries of the equilateral triangle. — Leila Sloman, Quanta Magazine, 3 Dec. 2025 See All Example Sentences for equilateral triangle

Word History

First Known Use

1614, in the meaning defined above

Time Traveler
The first known use of equilateral triangle was in 1614

Rhymes for equilateral triangle

See All Rhymes for equilateral triangle

Browse Nearby Words

equilaterally
equilateral triangle
equilibrant
See all Nearby Words

Cite this Entry

“Equilateral triangle.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/equilateral%20triangle. Accessed 1 Sep. 2026.

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