The simplest tetrahedron is made of four equal-sided triangles: one is used as the base, and the other three are fitted to it and each other to make a pyramid. But the great pyramids of Egypt aren't tetrahedrons: they instead have a square base and four triangular faces, and thus are five-sided rather than four-sided.
Example Sentences
Recent Examples on the WebOne group started chipping away at the foam volleyballs while another set about taping together basketballs into a tetrahedron.—IEEE Spectrum, 16 Nov. 2020 Mold that box into a pyramid or tetrahedron or any other everyday polyhedron.—Devin Powell, Discover Magazine, 20 Mar. 2019 That extraordinary hardness arises from a strong and inflexible structure: Five atoms form a tetrahedron and share electron pairs with each other.—Gemma Tarlach, Discover Magazine, 5 Apr. 2018 Many elements overlapped, forming a multidimensional sculpture: a triangle might jut out of a tetrahedron and meet another triangle at a point.—Kelsey Houston-edwards, Scientific American, 21 Sep. 2022 If the regular tetrahedron doesn’t tile space, the question becomes: Do any tetrahedra?—Quanta Magazine, 9 Feb. 2021 Triangles and tetrahedra are examples of more general shapes called simplices, which can be defined in any dimension.—Quanta Magazine, 13 Jan. 2015 That extraordinary hardness arises from a strong and inflexible structure: Five atoms form a tetrahedron and share electron pairs with each other.
3.—Gemma Tarlach, Discover Magazine, 23 Mar. 2018 With eight modules of tetrahedrons (triangular pyramids) made of translucent polyethelene and aluminum tubes that billow out from a symmetrical axis, the piece feels both organic and machinelike.—Molly Glentzer, Houston Chronicle, 10 Jan. 2018 See More
These example sentences are selected automatically from various online news sources to reflect current usage of the word 'tetrahedron.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.
Word History
Etymology
New Latin, from Late Greek tetraedron, neuter of tetraedros having four faces, from Greek tetra- + hedra seat, face — more at sit
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